electronics in motion and conversion december 2010 · hype of bouncing back from the downturn. my...

ZKZ 64717

12-10ISSN: 1863-5598

Electronics in Motion and Conversion December 2010

GvA Leistungselektronik GmbH | Boehringer Straße 10 - 12 | D-68307 Mannheim

Phone +49 (0) 621/7 89 92-0 | www.gva-leistungselektronik.de | [email protected]

SECURINGYOUR PROJECTSWelcome to the House of Competence.GvA is your expert in individual problem solutions for all sectors of power electronics – state of the art know how and profound experience as an engineering service provider, manufacturer and distributor.

Consulting – Design & Development – Production – Distribution

C O N T E N T S

Viewpoint

Toy Train Boxes are Open . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

News . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8

Blue Product of the Month

Hybrid Circuit Protection Technology Capable of 30A

Hold Currents and 100A Max

by Tyco . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Green Product of the Month

Half the Size of Conventional 1200 Volt IPM`s

by Semikron . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Guest Editorial

Zero No Load – Deliverable Today

By Doug Bailey VP Marketing, Power Integrations, Inc. . . . . . . . . 14

Market

Electronics Industry Digest

By Aubrey Dunford, Europartners . . . . . . . . . . . . . . . . . . . . . . . . . 16

Market

U.S. Leading in the Adoption of DC Building Power

By Linnea Brush, Senior Analyst, Darnell . . . . . . . . . . . . . . . . 18-19

Cover Story

Deadly Sins in Power Electronics

By Werner Bresch; GvA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-25

Power Modules

Making Wind

By Rainer Weiß, Application Manager and Ralf Herrmann, Product Manager at Semikron . . . . . . . . . . . . 26-28

MOSFET

UniFET II Optimized Power MOSFETs for Resonant Converters

By Wonsuk Choi, Sungmo Young and Denny Kim, Fairchild Korea Semiconductor . . . . . . . . . . . . . . . 29-33

Measurement

Acoustic Imaging for IGBT Reliability

By Tom Adams, Consultant, Sonoscan, Inc. . . . . . . . . . . . . . . 34-35

Power Management

Feedback Loop Op Amp Limitation Considerations

By John Bottrill, Senior Applications Engineer, Texas Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-38

MOSFET

Optimizing MOSFET Selection in Handset and

Portable DC Load Applications

By Ryan Zahn and Isauro Amaro, ON Semiconductor . . . . . . 40-41

New Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42-48

Bodo´s Power Systems® December 2010 www.bodospower.com2

TThhee GGaalllleerryy

Next generation inverter designs for renewable energy applications demand

reliable DC link capacitors with higher capacitance values, voltage, and cur-

rent ratings. Now available in new case sizes, Cornell Dubilier’s expanded

range of Type 947C power film capacitors meet or exceed the requirements

for bulk energy storage, ripple filtering and life expectancy for wind and

solar power inverter designs, as well as electric vehicle applications. Select

from hundreds of standard catalog listings, or connect with CDE engineers to

develop special designs to your requirements.

For sample requests or more technical information, visit www.cde.com/bodo

C A PAC I TO R S O L U T I O N S F O R P OW E R E L E C T R O N I C S

��

TYPE 947C POWER FILM CAPACITORS

85, 90 & 116 mm CASE SIZES

CAPACITANCE VALUES TO 1500 μF

APPLIED VOLTAGE TO 1300 Vdc

RIPPLE CURRENT RATINGS TO 100 Arms

M O R E O P T I O N S F O R P O W E R E L E C T R O N I C S

Bodo´s Power Systems® December 2010 www.bodospower.com

It’s time to begin reflecting on the past and

recharging for the upcoming year. I often

have fond memories of the toy trains that I

always unpacked prior to Christmas before

turning my parent’s living room into a fantasy

world. Inspirations that made me become an

engineer. Industry is desperate for engineers

but what are the companies doing to make

being an engineer attractive? And what are

we doing as individuals?

About 50 years ago I became interested in

electric trains and now my two grand

nephews are visiting and turning my office

space into their dream world. Plenty of

Marklin size 1 trains are still in my boxes.

The boys have fun and, for me, it’s great to

sit and listen to the two little engineers work-

ing on their layout. Teamwork and dialog are

essential. The older asks for one curve and

the younger one delivers two. The older one

complains that he ask for one curve, the

younger one says he heard it all right, but

brought two just in case. The toy trains are

always an indicator for me that winter is

close and Christmas is coming up fast. What

a motivation it is for me to work in a size 1

diesel and steam wonderland.

Visiting California last month and taking a

steam train ride from Roaring Camp near

Santa Cruz proves to me that the fascination

of steam will never end.

This year’s electronica showed busy and

healthy activity. People are looking forward

to a consolidated market in 2011 after the

hype of bouncing back from the downturn.

My schedule was completely filled with

meetings every half hour and I must apolo-

gize that not all requests could be filled. I did

my best to meet personally with as many of

you as possible and will follow up in coming

issues with the material collected at both the

electronica and SPS/IPC/DRIVES.

I’d like to thank all of my supporters both

inside and outside of my magazine. A strong

team continues handling process and

progress on the website, on the layout and

in printing the publication. But most impor-

tantly it is you, the readers and the industry,

that makes the publication a source for cru-

cial information to build your success in

design. The readership has expanded to

countries all around the world and reflects

the global market. It’s important to me, prob-

ably because of my Prussian upbringing,

that the magazine is delivered on time to all

including my overseas readers and thus,

they are sent by first class mail. Working like

a swiss clock makes it happen and it’s great

for me to get feedback from readers who say

they realize the new month has started when

my magazine arrives.

With this, my December issue - delivered, as

always, on time – we will have produced a

total of 726 pages this year: strong perform-

ance thanks to strong support.

My Green Power Tip for December:

Watch the polar bear and find out why he

does not hunt for penguins.

Hang your boots on the chimney and wait to

see what Santa brings.

Merry Christmas and a Happy New Year

Time to Unpack the ToyTrain Boxes Again!

V I E W P O I N T

4

A MediaKatzbek 17a

D-24235 Laboe, Germany

Phone: +49 4343 42 17 90

Fax: +49 4343 42 17 89

[email protected]

www.bodospower.com

Publishing EditorBodo Arlt, [email protected]

Creative Direction & ProductionRepro Studio Peschke

[email protected]

Free Subscription to qualified readers

Bodo´s Power Systems

is available for the following

subscription charges:

Annual charge (12 issues) is 150 €

world wide

Single issue is 18 €

[email protected]

circulation

printrun

25000

Printing by:

Central-Druck Trost GmbH & Co

Heusenstamm, Germany

A Media and Bodos Power Systems

assume and hereby disclaim any

liability to any person for any loss or

damage by errors or omissions in the

material contained herein regardless of

whether such errors result from

negligence accident or any other cause

whatsoever.

Events

Embedded World

Nuremberg, Ger.

March 1st-3rd

www.embedded-world.eu/

APEC 2010

Ft. Worth, TX, USA

March 6th -10th

www.apec-conf.org/

EMC2011,

Stuttgart/Ger.

March.15th – 17th

www.mesago.de/de/EMV/home.htm

New Energy

Husum Ger.

March17th-20th

www.new-energy.de

green building

San Jose CA

January 24th -26th

greenbuildingpower.darnell.com

Solutions for windpower systemsEnergy-efficient components for high system reliability

The Infineon product portfolio provides components for the highest energy efficiency in windmill power converter and pitch control solutions.

Our Power Modules with newest 1200V/1700V trench fieldstop IGBT4 and Emitter Controlled diode chip technology offer best in class power density solutions in conjunction with extended lifetime. The modules feature low on state losses, opti-mized soft switching behavior and a wide operation temperature range up to 150°C maximum junction operation temperature. The newly introduced stack assembly ModSTACK™ HD leads to more than 50% higher power density at same footprint.

The following benefits are provided to our customers:� Extended module utilization by 150°C maximum junction operation temperature� Highest power density� Supreme power cycling and thermal cycling capability

[ www.infineon.com/highpower ]

DC- Link Circuit

AC to DC Rectifier

DC to AC IGBT Inverter

ACSource

==

6 Bodo´s Power Systems® December 2010 www.bodospower.com

N E W S

Power Integrations announced a strategic

investment in SemiSouth Laboratories a Mis-

sissippi-based manufacturer of high-voltage

silicon-carbide (SiC) semiconductor devices.

Power Integrations' commitment of $30 mil-

lion, which includes an equity investment in

SemiSouth, a technology license and other

financial commitments, will help drive the

continued expansion of SemiSouth's SiC

fabrication facility and spur continued growth

of clean-tech jobs in Mississippi. The compa-

nies will collaborate to drive adoption of

SemiSouth's SiC technology, which enables

ultra-efficient power conversion for solar and

wind inverters, hybrid/electric vehicles and

other applications that benefit from excep-

tionally high energy efficiency.

"SemiSouth has made impressive break-

throughs in the development of silicon-car-

bide technology, attaining exceptionally high

levels of efficiency and establishing SiC as

an enabler of clean technologies such as

solar energy and hybrid/electric vehicles,"

stated Balu Balakrishnan, president and

CEO of Power Integrations. "With a mutual

focus on energy-efficient high-voltage semi-

conductor technology, Power Integrations

and SemiSouth are natural strategic part-

ners. We are particularly enthusiastic about

investing in Mississippi's emerging high-tech

sector, where strong support from govern-

ment and the academic community has cre-

ated an environment highly conducive to

innovation and private-sector investment."

Kenney Roberts, president and CEO of

SemiSouth stated "SemiSouth has recently

been recognized by its customers for having

world-record, cost-effective, energy-efficient

power semiconductor electronic products

based on SiC technology”.

www.semisouth.com

www.powerint.com

Power Integrations Strategic Investment in SemiSouth

CUI Inc announced that it is now a member

of the Distributed-power Open Standards

Alliance (DOSA).

DOSA is a global association dedicated to

furthering compatibility and standardization

in the DC-DC board mounted power conver-

sion market. Current members include

founding members Lineage Power and Syn-

Qor as well as AcBel, Bel Power, Delta Elec-

tronics, Emerson Network Power, Ericsson

Power Modules, FDK, Murata Power Solu-

tions, NetPower Technologies, Power-One,

TDK-Lambda and Wall Industries.

As a technology company dedicated to the

development, commercialization, manufac-

ture, and distribution of innovative electronic

components, acceptance into DOSA serves

to highlight CUI’s commitment in providing

competitive power products to a global mar-

ket. CUI’s power line, V-Infinity, encompass-

es board level dc-dc converters, embedded

ac-dc power supplies, and external ac-dc

power adapters that range from 0.25 to 2400

watts with a focus on the networking, med-

ical, consumer, and industrial markets.

www.cui.com

CUI Now a Member of DOSA

Infineon Technologies has won the Bavarian State Award for Electric

Mobility. Martin Zeil, Bavarian Minister of Economics, Infrastructure,

Transport and Technology, presented the award to Peter Bauer, CEO

of Infineon Technologies AG, yesterday evening. The ceremony at

which the awards were conferred in altogether seven categories was

held alongside the eCarTec International Trade Fair for Electric Mobil-

ity in Munich. The award went to Infineon in the “Drive Technology”

category for the company’s microcontrollers ensuring smooth and

hence efficient operation of the motor in electric bicycles, the so-

called e-bikes. In addition, Infineon was also nominated for its active

battery balancing solution in the “Storage Technology/System Integra-

tion” category.

“Infineon’s microcontrollers form the centerpiece of the drive in the e-

bike. In 2009, some 25 million e-bikes were sold in China, the world’s

largest nation of cyclists. About every third e-bike incorporates chips

from Infineon”, said Peter Bauer, CEO of Infineon Technologies AG.

“The Bavarian State Award for Electric Mobility is recognition of our

work. It underlines that mobility and the responsible use of resources

are of the greatest relevance to society – all the more reason for our

delight at this accolade.”

Infineon’s chips are instrumental in reducing the cost of the drive and

electronics in the e-bike and in boosting the energy efficiency of the

overall system. The XC800 family enables Field Oriented Control

(FOC) and hence smooth, efficient operation of the motor. Infineon’s

8-bit microcontrollers deliver the performance of larger and more

expensive 16-bit and 32-bit chips. These features are pivotal in the

very small and cost-critical drives for e-bikes.

www.infineon.com/electromobilit

Infineon Wins Bavarian State Award for Electric Mobility

www.bodospower.com December 2010

The International Electrotechnical Commis-

sion announced it will launch its online IEC

Smart Grid Standard Mapping Solution. This

multidimensional interactive tool will create a

map of the smart grid and enable smart grid

managers around the world to quickly identi-

fy IEC international smart grid standards,

position them in relation to their role in the

smart grid, and point out possible interac-

tions and overlaps. The announcement was

made at the GridWeek conference, during a

panel discussion on Global Markets and

Global Standards for the smart grid.

The mapping solution will launch by the end

of 2010 or early 2011, and has already been

recognized by major smart grid standard

players [United States' National Institute of

Standards and Technology (NIST), CEN

CENELEC, and others].

The IEC currently provides the large majority

of all standards needed to build the smart

grid, with new standards being brought into

the portfolio on an ongoing basis. The IEC is

bringing relevant national or regional stan-

dards via a fast track system into the inter-

national consensus process. Gradually the

new mapping solution will allow other organi-

zations to add their own standards in layers

in addition to IEC international standards.

"The smart grid represents a technical chal-

lenge beyond building infrastructure, and

can't reach its potential if every country and

company is building it based on different

standards," said Jacques Régis, IEC Presi-

dent. "Our international set of standards

ensures the smart grid industry can grow

and function as one coordinated entity, rely-

ing on optimal compatibility and the ability of

one system or device to communicate with

others."

www.iec.ch

IEC Online Smart Grid Standard

Mapping Solution

PCIM Europe 2011

International Exhibition & Conference on

POWER ELECTRONICS – INTELLIGENT

MOTION - POWER QUALITY

Nuremberg, 17 - 19 May 2011

Stuttgart/Nuremberg, 4 October 2010:

The PCIM Europe board of direc-tors has

two new members and a new chairman.

After five years at the top of the committee

Prof. Dr. Alfred Rufer of the renowned EPFL,

École Poly-technique Fédérale de Lausanne

handed over the responsibility to Prof. Dr.

Leo Lorenz, Infineon Technologies. New in

the board of directors are Dr. Eric Favre,

Vice President Technology of LEM and Prof.

Dr. Philippe Ladoux of University of

Toulouse.

Dr. Eric Favre (48) was ten years at ETEL,

Neuchâtel, acting as an expert engineer and

in charge of the aerospace division, deliver-

ing high perform-ance motion control for var-

ious satellites applications. In year 2000 he

joined the LEM group in Geneva, leading the

research and development. As an expert for

intelligent motion Eric Favre is committed to

numerous international research programs

and scientific committees.

Prof. Dr. Philippe Ladoux (47), teaches

power electronics at the Grande École INP-

ENSEEIHT (École Nationale Supérieure

d’Électrotechnique, d’Électronique, d’Infor-

matique, d’Hydraulique et des Télécommuni-

cations) in Toulouse. At the moment, he is in

charge of research programs concern-ing

power electronics and railway traction at the

LAPLACE, Laboratory on Plasma and Con-

version of Energy.

www.pcim.de

Change in the PCIM Europe

Conference Board


N E W S

The power module production capacity at Danfoss Silicon Power in

Schleswig, Germany has been expanded with 600 m² in November,

2010. After this expansion, all available space in the 4,500 m² build-

ing is fully utilized. Nonetheless, this expansion is not sufficient to

meet the extremely high demand for power modules, also after 2015.

Therefore, we are expanding the power module capacity in Danfoss

Silicon Power by movimg from Schleswig to the facilities in Flens-

burg, Germany, which were formerly owned by Motorola.

This expansion is yet another step in creating a strong power elec-

tronics center in the Danish/German border region. Danfoss also

expands the solar inverter capacity by moving production to Nord-

borg and the resource center for frequency converters and solar

inverters in Gråsten as earlier informed.

The new premises in Flensburg include about 18,000 m² production

and logistics area and 9000 m² office area. Although they are modern

and have been used for production of electronic devices before, they

are to be prepared for clean room production in order to comply with

the high TS16949 quality standards of power module production.

The move will start in second quarter 2011 and be completed in

2012.

Danfoss Silicon Power plans to create about 200 jobs additionally

within power electronics in Flensburg by 2015.

Siliconpower.danfoss.com

Danfoss Silicon Power Moves to Flensburg

National Semiconductor announced that it is collaborating with Sun-

tech Power Holdings the world’s largest producers of crystalline sili-

con solar panels, to develop “smart panel” technology, incorporating

National Semiconductor’s award-winning SolarMagic power optimizer

chipset into Suntech solar panels to improve the power output of

solar systems.

"Suntech was one of the first companies to recognize the value that

integrated high-performance microelectronics brings to a photovoltaic

panel. We are proud of our collaboration with Suntech to develop a

next-generation product that will embed SolarMagic technology inside

the junction box and ultimately boost the performance of solar

arrays," said Michael Polacek, senior vice president, Key Market

Segments and Business Development for National Semiconductor.

National’s SolarMagic power optimizer chipset enables each solar

module to produce the maximum energy regardless of whether other

panels in the array are under-performing due to environmental mis-

match. The technology enhances the energy harvest of each individ-

ual PV panel through a combination of advanced algorithms and

leading-edge analog power management circuit techniques. In real-

world tests involving shading and mismatch, Suntech modules with

SolarMagic power optimizer technology were shown to recoup an

average of 50 percent of lost energy, and in some cases captured as

much as 75 percent of otherwise lost energy compared to standard

panel performance.

Suntech recently utilized SolarMagic power optimizers with its panels

on the eco-friendly Suntech Guosheng, a solar energy-powered

water vessel ferrying passengers at the Shanghai World Expo.

www.suntech-power.com

www.national.com

Collaboration to Develop ‘Smart Panel’ Technology

Silicon Laboratories announced the acquisi-

tion of Ireland-based ChipSensors Limited,

an early stage technology company creat-

ing innovative single-chip CMOS sensors

designed to detect temperature, humidity

and gases. ChipSensors' technology com-

plements Silicon Labs' touch, proximity

sensing and recently acquired MEMS tech-

nology, expanding the company's capabili-

ties in CMOS-based sensors.

ChipSensors, a fabless semiconductor company, has an experienced

management and technology team with extensive materials science

and mixed-signal design expertise. The company has leveraged

these capabilities to develop novel sensor technology that addresses

a wide range of target markets such as thermostats, automotive cli-

mate control, printers, wireless sensor networks, security systems,

gas leak detectors, white goods, and food and drug transportation.

Historically, sensors have been manufactured using specialized

materials and manufacturing processes that demand external support

circuitry and post-assembly calibration. ChipSensors' proprietary,

patented technology can enable the sensors, signal conditioning cir-

cuits and RF transceiver functions, together with the microcontroller

and memory, to be integrated and calibrated in a single CMOS IC.

These highly integrated devices provide a cost-effective solution to

precision sensing for high-volume applications.

www.chipsensors.com

www.silabs.com

Silicon Labs acquires ChipSensors


B L U E P R O D U C T O F T H E M O N T H

Tyco Electronics a global leader in circuit protection solutions,

announced the introduction of a Metal Hybrid PPTC (MHP) technolo-

gy useful for high-rate-discharge battery applications at ratings above

30VDC/30A such as cordless power tools, e-bikes and back-up

power supplies. MHP technology uses a new hybrid circuit protection

approach that combines a bimetal protector in parallel with a poly-

meric positive temperature coefficient (PPTC) device. This integrated

solution provides resettable overcurrent protection and utilizes the

low resistance of the PPTC device to help prevent arcing in the

bimetal protector at higher currents, while also heating the bimetal to

keep it open and in a latched position.

Due to advances in lithium ion (Li-ion) technology, smaller, lighter

weight, and higher power Li-ion batteries can now replace nickel

cadmium or lead acid batteries previously used in high-rate-dis-

charge battery applications. This trend has resulted in a rapidly

expanding market for high-rate-discharge Li-ion battery applications,

which, in turn, has created the need for cost-effective, robust circuit

protection devices that help ensure battery safety in end-products.

However, few protection solutions address high-rate-discharge bat-

tery applications and traditional circuit protection techniques tend to

be large, complex and/or expensive. In response, MHP technology

provides a cost-effective, space-saving device that conventional cir-

cuit protection approaches are unable to deliver.

The initial product in a planned family of MHP devices, the MHP30-

36 device, has a 36VDC/100A maximum rating and a time-to-trip of

under five seconds at 100A (at 25 degrees C). The device’s hold cur-

rent is 30A and the initial resistance is under two mOhms.

The MHP30-36 device offers excellent arc suppression characteris-

tics compared to standard breaker devices that must limit the number

of switching cycles since arcing between contacts may damage

them. The MHP30-36 device can also help reduce the number of dis-

charge FETs and accompanying heat sinks in applications that typi-

cally use IC-plus-FET battery protection designs.

“Available in a convenient small form factor, the MHP30-36 device

provides a rugged, resettable circuit protection solution that offers

battery pack designers and manufacturers a method to optimize

space, reduce cost, enhance safety and help meet future battery

safety requirements,” said Ty Bowman, Global Battery Market

Manager.

The MHP device technology can be configured for various applica-

tions, and higher voltage (up to 400VDC) and hold current (60A)

devices are currently in development. Future design considerations

include battery protection in Li-ion battery packs used in e-scooters

and light electric vehicles (LEVs), as well as standby-power applica-

tions and non-battery applications such as electric motor protection.

Tyco Electronics Ltd. is a leading global provider of engineered elec-

tronic components, network solutions, specialty products and under-

sea telecommunication systems, with fiscal 2009 sales of US$10.3

billion to customers in more than 150 countries. Tyco designs,

manufacture and market products for customers in a broad array of

industries including automotive; data communication systems and

consumer electronics; telecommunications; aerospace, defense and

marine; medical; energy; and lighting. With approximately 7,000

engineers and worldwide manufacturing, sales and customer service

capabilities, Tyco Electronics' commitment is our customers'

advantage. More information on Tyco Electronics can be found at:

www.tycoelectronics.com

Hybrid Circuit Protection Technology Capable of

30A Hold Currents and 100A Max

MAKING MODERN LIVING POSSIBLE

DAN FO S S S I L I CON POWER SILICONPOWER.DANFOSS.COM

The future of cool designMove into the fast lane with customized power modules

offering: Low weight, compact design, extended life and very low life cycle costs.In short, when you choose Danfoss Silicon Power as your supplier you choose a thoroughly tested solution with unsur-passed power density. Day in and day out. Please go to siliconpower.danfoss.com for more information.

It cannot be stressed enough: Efficient cooling is the most important feature in power modules. Danfoss Silicon Power’s cutting-edge ShowerPower® solution is designed to secure an even cooling across base plates. In addition, our modules can be customized to meet your automotive requirements in detail,

ShowerPower®

The MiniSKiiP IPM from Semikron sets a

new benchmark for power density in 1200V

Intelligent Power Modules. At a weight of

55g and a volume of 49cm³, this module is

lighter and more compact than any other

IPM module in this power class. Plus, the

design yields optimum switching properties

with regard to electromagnetic interference.

This module was developed for inverter

applications of up to 15kW.

With an area of 59mm x 52mm and an over-

all height of 16mm, this module is at least

fifty percent smaller than conventional intelli-

gent power modules in this power range.

The innovative connection technology allows

for the development of compact inverters

and reduced production costs.

To achieve the high power density offered in

the MiniSKiiP® IPM module, the power semi-

conductor chips and the DCB are thermally

connected to the heat sink by way of an effi-

cient pressure contact system. Since the

module does not contain a base plate, the

thermal resistance is much lower than in any

other IPM with base plate.

The integrated SOI driver is mounted directly

onto the DCB and connected to the gate ter-

minals of the power transistors by short con-

ductor lines via optimised gate resistors.

These short connections ensure harmonious

switching behaviour and reduce electromag-

netic interference. As a result, less complex

protection measures are needed to comply

with the electromagnetic compatibility

requirements. The short paths result in low

parasitic inductances, which in turn mean

lower over-voltages in the module, allowing

for higher DC link voltages and greater effi-

ciency.

The MiniSKiiP® IPM module and the power

circuit board are mounted to the heat sink

using a single standard screw. The entire

power, gate and auxiliary connections are

made by way of pressure contacts to the

PCB rather than soldered contacts. This

allows for quick and cost-reduced assembly.

Plus, the removal of solders further improves

the quality of the entire construction and

brings about a higher degree of reliability

than in conventional IPM modules. Users

profit from the user-friendly design of this all-

inclusive product as compared with discrete

solutions.

The 1200V 6-pack MiniSKiiP® IPM has a

high-voltage driver IC and features state-of-

the-art Trench-Field-Stop IGBTs, which are

optimised for low switching losses and high

current densities. At a rated current of 61A,

an output power of up to 15kW is possible.

600V Converter-Inverter-Brake versions are

also available. The modules fully comply

with the requirements of the EU RoHS direc-

tive.

Semikron is an internationally leading power

semiconductor manufacturer. Founded in

1951, the German-based family enterprise

employs 3200 people worldwide. Semikron

comprises a global network of 35 companies

with production plants in China, Korea, India,

South Africa, Brazil, USA, Italy, France, Slo-

vakia and Germany that guarantees fast and

competent on-site customer care.

The products range from chips, discrete

semiconductors, transistor, diode and thyris-

tor power modules to customer specific solu-

tions and integrated power electronic sys-

tems for applications from one kilowatt into

the Megawatt range. Semikron is the market

leader in the field of diode/thyristor semicon-

ductor modules, enjoying a 37% share of the

worldwide market. (Source: IMS Research

„The worldwide market for power semicon-

ductor discretes and modules“2008).

Semikron technology powers nearly half of

the globally installed wind power capacity.

According to a survey carried out by BTM

Consult ApS, the total wind power capacity

installed until 2009 was 122 Gigawatt. 57

Gigawatt comprises semiconductors from

Semikron. “Semikron inside” has become a

trademark for markets such as industrial

drives, power supplies, renewable energy,

battery vehicles and the rail industry. The

dedication to the electric and hybrid vehicle

market was further strengthened with the

50/50 joint venture between Semikron and

Magna Electronics and the majority take-

over of Compact Dynamics GmbH. As a sig-

nificant innovator in the power electronics

sector, many of Semikron’s progressive

developments have been accepted as

industrial standards.

www.semikron.com

G R E E N P R O D U C T O F T H E M O N T H


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PowerfulThis is the right place for you!

Power for Efficiency!


About 10 years ago, researchers at

Lawrence Berkeley National Laboratory

decided to study how much energy was

being wasted by electronic equipment sitting

in standby mode, doing no useful work. They

were shocked to discover that about 10% of

all power generated was burned in this way.

The conclusions of that study and other

research spawned international meetings

between government regulators, eco-

researchers and industry representatives,

and a regulatory process followed that

imposes limits on standby power usage. This

resulted in several generations of power

supply products, each featuring decreasing

standby power drain as the regulations tight-

ened and technology improved. Power Inte-

grations is a leader in developing the

required energy-efficient ICs, and to-date we

have sold about several billion chips contain-

ing our innovative EcoSmart™ technology.

A very interesting fact however, is that many

OEMs have been buying these power saving

chips not because they have to, but because

they want to. Increasingly, it is not the regu-

latory authorities that are leading the pace in

power saving, but the OEMs themselves. In

many brand name consumer product com-

panies, there are managers taking a serious

view of global energy consumption and

many now demand power consumption

characteristics significantly better than the

government-mandated specifications require.

For example, several major OEMs producing

TVs and monitors have set a de-facto

standard of 100mW maximum standby

consumption; ten times lower than the

Energy Star requirement.

You would be forgiven for taking the view

that OEMs may be cynically exploiting green

issues to gain a marketing advantage. But

these OEMs seem to make little or no men-

tion of the energy saving benefits in their

product promotion and packaging. They

focus instead on the more traditional user

features and value of their products. The

issue of ultra low standby consumption is

something worked on quietly between their

developers and the suppliers of power sup-

ply components.

One should conclude there is a genuine

commitment to drive down energy consump-

tion within the electronics industry and cer-

tainly among the major OEMs. They are

making the change because it is the right

thing to do. It also helps that reducing stand-

by power is really a matter of careful design

and appropriate power IC choice. It costs lit-

tle more than the will to change and an inno-

vative attitude to have green standby per-

formance.

A study by Nokia found that up to two thirds

of energy consumed by cellphones was

wasted by chargers left plugged in. Conse-

quently, the world’s top cell phone manufac-

turers (Nokia, Samsung, Sony Ericsson,

Motorola and LG Electronics) and the Euro-

pean Commission Integrated Policy Program

produced a star rating system for chargers.

At the bottom with zero stars were chargers

consuming more than 0.5W and at the top of

the range with 5 stars were chargers con-

suming less than 30mW. The star rating sys-

tem was launched in 2008. We can now go

more than ten times better.

Last month, we released LinkZero™-AX, a

power supply IC based on our low-cost AC-

DC converter products that has the ability to

switch off, thereby consuming 0.00 W of

power in standby mode. There is no interna-

tional standard or regulation that requires

zero standby power usage for any products,

and developers have not yet asked for such

a part. We made one anyway.

I’ve pondered our motives and the best

explanation that I can think of is that we

have faith in engineers. We have faith that

engineers care about the environment, faith

that they are free to make choices in the

products that they design, and faith that

someone out there will recognize the value

of a product that takes no power in standby

mode, and find an innovative way to make

use of it. The best part of this development

is that the circuit is no more complex or

expensive to implement than the old-fash-

ioned, power-hungry version – all that was

needed was creativity to conceive it and the

commitment to make it happen.

Of course, the same effect can be achieved

simply by pulling out the plug or throwing a

mains switch, but consumers simply do not

behave in this way just to save a little ener-

gy. You cannot blame them when virtually all

consumer equipment is operated with a

remote control. It’s far better to leverage

engineering brains than to rely on the con-

sumer’s initiative, and invent a better way.

LinkZero™-AX ICs enable us to keep our

easy-to-reach “soft” on-switches and con-

venient IR remote controls, but waste

virtually no electrical energy while doing so.

To share ideas visit the PI Forum and join

the discussion on standby power usage. Let

us know whether you think our new product

is the solution to achieving zero standby

power and how you would use it.

www.powerint.com

G U E S T E D I T O R I A L

Zero No Load – Deliverable TodayBy Doug Bailey VP Marketing, Power Integrations, Inc. (San Jose, CA)

15www.bodospower.com December 2010 Bodo´s Power Systems®

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GENERAL

With a value of € 217

billion in 2009, Europe

still accounts for 19

percent of the € 1,115

billion global produc-

tion of electronic

equipment, so Deci-

sion, a Paris based

consulting company.

With a fall in production of 13.9 percent in

2009, the European electronics industry has

been hit hard by the global economic reces-

sion. Contrary to the 2001 crisis, profession-

al application sectors such as automotive

and industrial were not immune to the global

economic recession. This left

aerospace/defense and security as the only

sector of European electronic production to

achieve positive growth in 2009. Looking

ahead, Europe will have a modest growth

starting from 2010 and rapidly reaching an

average trend of 2.5 percent between 2009

and 2014.

SEMICONDUCTORS

Measured in Euro, European semiconductor

sales were € 2.525 billion in September

2010, up 1.4 percent on the previous month

and up 38.0 percent versus the same month

a year ago, so the WSTS. On a YTD basis

semiconductor sales increased by 40.3 per-

cent in 2010. Measured in dollar, third-quar-

ter sales were up by 5 percent from the sec-

ond quarter, totalling $ 9.774 billion.

Power Integrations, a supplier in high-volt-

age integrated circuits for energy-efficient

power conversion, announced a strategic

investment in SemiSouth Laboratories, a

Mississippi-based manufacturer of high-volt-

age siliconcarbide (SiC) semiconductor

devices. Power Integrations' commitment of

$ 30 M includes an equity investment in

SemiSouth and a technology license.

Prof. Dr. Herbert Reichl has been selected

as recipient for the European SEMI Award

2010. The award was presented during

Semicon Europa 2010 in Dresden, Germany.

Reichl is being recognized for over 20 years

of contributions to advanced semiconductor

packaging technologies.

Ecole Polytechnique Fédérale de Lausanne

and IBM announced a major research initia-

tive, with several academic and corporate

research organizations across Europe

including Infineon and Globalfoundries, to

address the alarming growth of energy con-

sumption by electronic devices. The

research project, called Steeper, aims to

increase the energy efficiency of these

devices, when active, by 10 times and virtu-

ally eliminate power consumption when they

are in passive or standby mode. The devel-

opment of energy-efficient steep sub-thresh-

old slope transistors that can operate at sub-

0.5 V operation domain will be a critical fac-

tor in the success of the project. To achieve

this, scientists will study the development of

socalled TFETs based on silicon (Si), silicon-

germanium (SiGe) and III-V semiconducting

nanowires.

OPTOELECTRONICS

Plastic Logic and the Leibniz Institute for

Polymer Research Dresden (IPF) are

extending their cooperation as part of a proj-

ect sponsored by the Federal Ministry for

Education and Research. The extension of

their collaboration is set for three years. The

main focus is the joint development of new

methods for analyzing organic electronic

components, as well as supporting the

development of organic dielectric materials.

These materials, for example, are used in

flexible displays such as those manufactured

by Plastic Logic.

PASSIVE COMPONENTS

July sales for Germany's printed circuit

board (PCB) industry were up 31 percent

compared to July last year, and cumulative

sales for the first seven months of this year

were up 33 percent, so the ZVEI. New

orders, likewise, were on the rise. While May

2010 saw a peak in order volume, July sur-

passed this by a further 40 percent. Com-

pared to July last year, orders were up 93

percent.

Industry observers attribute this growth to

unusually high order bookings, as well as

the general economic recovery, especially in

the automotive industry. The renewable

energy industry is also fuelling this growth,

especially the photovoltaics segment. Book-

to-bill ratio was up at 1.96-an all time high in

20 years that this indicator was established.

OTHER COMPONENTS

Hitachi and Johnson Controls have signed a

memorandum of understanding to work

together on several fronts in the field of

advanced energy storage. The companies

will study opportunities for collaboration in

the fields of motive and non-motive

advanced energy storage including Lithium-

ion batteries, exploring potential cooperation

across a wide span of initiatives including

R&D, procurement, production, marketing,

sales and standardization.

Digital Power has announced a definitive

agreement to purchase the intellectual prop-

erty (IP) and production packages of the

compact peripheral component interface

(Compact PCI, or CPCI) 600W AC/DC

power supply series from Telkoor Power

Systems, Israel, a global supplier in the

development and manufacture of high-grade,

high-density power supply solutions for mili-

tary and commercial applications.

EMS PROVIDERS

The global EMS market is projected to grow

at an annual average rate of 12.2 percent

through 2014, so New Venture Research

(NVR), formerly Electronic Trend Publica-

tions.

IPC's own forecast of assembly market

growth in North America projects a spike of

28 percent in 2010 as recovery takes hold,

and a return to more normal growth of 12

percent in 2011.

DISTRIBUTION

EnOcean, headquartered near Munich (Ger-

many), has awarded Unitronic, headquar-

tered in Düsseldorf, the distinction of 'Distrib-

utor of the Year 2010' in recognition of out-

standing performance in the marketing of its

batteryless radio sensors. Unitronic, founded

in 1969, is a member since 2002 of the

Swedish holding Lagercrantz Group.

Everlight Electronics appointed Bert Loburg

to the newly created position of Director, Dis-

tribution Management EMEA. Focal points of

his new role will be a structural revision of

the company's distribution management, to

prepare the sales channel organisation for

further growth and to develop and introduce

additional professional distribution tools.

This is the comprehensive power related

extract from the «Electronics Industry

Digest», the successor of The Lennox

Report. For a full subscription of the report

contact:

[email protected]

or by fax 44/1494 563503.

www.europartners.eu.com

M A R K E T

ELECTRONICS INDUSTRY DIGESTBy Aubrey Dunford, Europartners


The use of dc powering in buildings is relatively new, but it is receiv-

ing a lot of attention by large companies who see it as a way to

improve efficiency at both lower-voltage (24V) and higher-voltage

(380V) levels. Various regions have shown strong support of dc build-

ing power, with building integrated photovoltaics (BIPV) deployments

in Europe and residential dc power in Japan. But the U.S. is now tak-

ing the lead to promote both commercial and residential use of dc

power in buildings, with two recent developments expected to further

support its use.

The addition of dc power delivery systems to homes, office buildings

and commercial facilities offers the potential for significant improve-

ments in energy delivery efficiency, reliability, power quality and cost

of operation. Most of these facilities are currently dominated by fixed

overhead lighting and a variety of electrical devices that are typically

wired for the building’s lifetime rather than the occupants’ or resi-

dents’ evolving needs. As a result, building designers and owners are

looking for systems to make buildings more adaptable.

In addition, integration of infrastructure, equipment and furnishings

can improve energy efficiency. Addressing these concerns will lead to

the further deployment of new power, control and device-level tech-

nology designed for commercial interiors and developed around the

use of safe low-voltage direct current power. Although opportunities

exist in both new installations and retrofits, according to the EMerge

Alliance, 80% of the market opportunities are in the updating and

retrofitting of commercial buildings.

In 2009, the EMerge Alliance released the first dc power standard for

commercial buildings. According to the organization, the selection of

24Vdc provides the dual benefits of flexible, modular wiring and safe,

efficient power distribution. Also, many digital devices used within

commercial interiors today that inherently use dc power – such as

occupancy and daylighting sensors – are already based on this volt-

age.

The EMerge Alliance industry standard also allows buildings to adapt

to future energy needs by defining critical physical and electrical

requirements. The goals include changes in occupied spaces, move-

ment towards interoperable device-level controls and smart grid inte-

gration at the building level. Standard 1.0 establishes a more efficient

means of powering the rapidly increasing number of digital, dc-pow-

ered devices, such as sensors, lighting and IT equipment found in

today’s workplaces. It creates an integrated, open platform for power,

interior infrastructures, controls and a wide variety of peripheral

devices to facilitate the hybrid use of ac and dc power within build-

ings.

In November, 2010, the EMerge Alliance announced the first set of

26 EMerge Alliance Registered products at the U.S. Green Building

Council’s annual International Conference and Expo. According to the

Alliance, by evaluating and registering products for compliance to

EMerge Alliance standards, the Alliance and its members are deliver-

ing opportunities for commercial buildings, both new construction and

renovation, to be more energy efficient and sustainable. The regis-

tered products are compliant with the 24Vdc power room-level stan-

dard, and integrate power, infrastructures, controls and peripherals

into a microgrid platform to facilitate the hybrid use of ac and dc

power in commercial interiors. Companies include Armstrong World

Industries (infrastructure); Cooper Lighting (peripherals); Finelite

Lighting (peripherals); Lunera Lighting (peripherals); Nextek Power

Systems (peripherals and power); and Tyco Electronics (infrastruc-

ture). Additional products from Cooper Lighting, Nextek Power Sys-

tems, Northwire, OSRAM SYLVANIA and ROAL Electronics have

been submitted to the Alliance’s Registration and Evaluation pro-

gram.

For example, the New York-based Nextek Power Systems Company

installed a high-efficiency lighting system in a Frito Lay distribution

center. This LEED gold-rated facility was equipped with a lighting

system that utilized dc fluorescent ballasts, roof-integrated solar pan-

els, occupancy sensors, and daylight sensors for the highest possible

efficiency. Advanced building controls, energy-efficient lighting, a

highly efficient mechanical system, optimal interior day-lighting, and a

well-insulated envelope have all contributed to a 55% savings in

energy use compared to a conventional facility.

Good opportunities exist for the use of low-voltage dc distribution as

part of a hybrid ac and dc power structure for industrial, commercial,

government, and even residential buildings. The deployment of a dc

power operating system as part of an ac-dc hybrid building or as part

of a dc power microgrid island that can operate independently of the

bulk power grid could enhance the reliability and security of an elec-

tric power system.

On the high-voltage side, a preliminary test by the Electric Power

Research Institute (EPRI) of a dc power system at a Duke Energy

data center in Charlotte, North Carolina, found that the system uses

15% less electricity than the existing ac power system. The U.S.

Environmental Protection Agency (EPA) reported to Congress that

data center industry power consumption doubled from 2000 to 2006

and was expected to double again over the next five years. Duke

Energy’s Development Group said, “If this dc technology was imple-

mented in all those data centers, the impact could be significant.”

M A R K E T

U.S. Leading in the Adoption ofDC Building Power

By Linnea Brush, Senior Research Analyst, Darnell Group

www.bodospower.com Decewww.bodospower.com Septewww.bodospower.com

For the Duke Energy demonstration project, the data center’s 480Vac

was converted to 380Vdc and delivered to the equipment racks via a

380Vdc bus. The 15% energy savings provides a good benchmark

for the industry because the 480Vac system configuration is “typical

for data centers across the United States.” Dc-powered data centers

provide increased energy savings by eliminating multiple power con-

version stages, according to EPRI. Through similar circuit elimination,

the data center servers are also made more efficient. An EMerge

Alliance 380Vdc standard is expected to be approved in early 2011,

which should further support these types of data centers..

“Dc microgrids” can be implemented throughout buildings. EPRI iden-

tifies 24Vdc for occupied space, 380Vdc for data centers and building

services, and both 24Vdc and 380Vdc for outdoor spaces. Uses for

24Vdc include lighting and consumer electronics (TVs, PCs, projec-

tors); while 380Vdc is finding application in telecom central offices,

variable speed drives (washers/dryers/air conditioning), other home

appliances (stoves, ovens), and “rapid chargers” for plug-in electric

vehicles. The benefits of 380Vdc, in particular, include higher reliabili-

ty (fewer conversions/fewer points of failure); higher efficiency power

supplies and uninterruptible power supplies; no power distribution

unit transformer needed; smaller size; better power quality; and easi-

er integration of renewable energy. Worldwide, 380Vdc demos exist

in the United States, France, Sweden, Japan and New Zealand.

The 4th Annual Green Building Power Forum (GBPF), hosted by Dar-

nell Group in San Jose, California, in January, 2011, will focus on the

still-emerging issues related to dc powering of buildings. These

include: selection of the optimal dc distribution voltage; integration of

distributed generation resources; maximizing overall efficiency; dc

lighting systems; dc HVAC and other building systems; dc appli-

ances; building automation and controls; dc microgrids; advanced

components and hardware; safety considerations; standardization

issues; and hybrid ac and dc power distribution architectures. GBPF

has become “the place to be” for new technologies and roadmaps

related to dc building power and other “green” power solutions.

As dc powering of buildings evolves, opportunities will extend to

other applications, such as energy harvesting and coupling native dc

renewable energy sources to dc microgrids. This shift from ac power

to dc power involves a paradigm shift in thinking, as well. Many fac-

tors are driving the need to at least look at a hybrid ac power/dc

power approach, and these types of facilities are likely to pave the

way for “pure” dc powering. The ZigBee standard has helped the

adoption of wireless sensor technologies, and the EMerge standard

is expected to do the same for dc building power.

http://greenbuildingpower.darnell.com/

You don’t believein poltergeist...


All the more remarkable then to note that sometimes inadvertence or

minor design negligence thwarts these efforts. In many cases, this

can be attributed to the requirement to minimise manufacturing costs

for the design – with the result that a few cents are saved at a certain

point at which perhaps no savings should have been made.

Clamping systems for power semiconductors, regulated

pressure brings performance.

It should really be accepted that this issue is actually old hat. But

practical applications are demonstrating time and time again that

approaches are being used, particularly with clamping systems,

which, to put it cautiously, are dubious to say the least. Often,

designs in which only one tension bolt is used for two disc cells

(which are popular, for example, in the W1C AC controller configura-

tion) materialise as a result of cost pressure. A well made clamping

device simply requires a slightly higher financial commitment which

pays for itself quickly if potential failures in the field can be prevented

as a result.

To clarify why a clamping system must satisfy certain minimum

requirements, it is really important to be familiar with the internal

structure of a disc cell. Inside the disc cell is a silicon wafer which is

either alloyed onto a molybdenum disk on the anode side or which

lies loosely between two molybdenum disks as a so-called “free pres-

sure contact”. In turn, these molybdenum disks lie between the thick

copper anodes and cathodes of the disc cell housing. There is often

a thin foil (e.g. silver) between the molybdenum and copper which

acts as a ductile intermediate layer between the individual internal

materials and which is important in attaining the inner thermal transi-

tion resistances specified in the data sheet. Disc cells are available

today with pressure contact diameters of approx. 20 mm to approx.

150 mm. The overhead associated with a 150 mm pressure contact

is of course higher than with a 20 mm pressure contact.

The following are required from the clamping devices/assem-

blies:

Reliable electrical insulation from the anode to cathode side

(dependent on the inverse voltage of the power semiconductor

deployed and the resulting application voltage).

Reliable application of the contact pressure required, which can now

be up to approx. 180 kN depending on the size of the power semi-

conductor. The pressure thrust bearings may not bend under the ten-

sile stress - the tension bolts must be able to withstand the tensile

stress. The spring elements may not compress in all the way.

The thrust bearings, pressure distributors, insulators and the cooling

units on the anode/cathode sides must have sufficiently good pres-

sure-time stability under load, even in high application temperatures.

The materials used may not slide away under pressure. This applies

in particular when so-called columns with multiple disc cells are

braced with one clamping device. Never install columns horizontally

into the control cabinet. Shearing forces may result which can

fracture the silicon wafer in the disc cell.

The contact pressure must be applied across the whole surface of

the disc cell. It may under no circumstances be applied eccentrically

or even at individual points. Usage of a pressure distributor is a sen-

sible option here – especially for large disc cells.

The contact pressure must be applied centrically onto the disc cell,

even if the tension bolts are not tightened evenly (within limits). In

addition to the pressure distributor already mentioned, the use of an

additional compensator is a sensible option, especially when using

larger disc cells, to effectively prevent uneven pressure distribution.

Uneven tightening of the tension bolts must be avoided. Otherwise,

this poses the risk of the silicon wafer breaking.

C O V E R S T O R Y

Deadly Sins in Power ElectronicsDifferent life expectancies can be assumed

for different design technologies

Power semiconductors can be found in many applications providing high performances in a targeted, managed and reliable manner. Great effort is made in development departments to ensure that the power electronics devices developed there meet the

requirements of practical applications. In many cases, development costs incurred thisway can be considerable, as can the costs for hardware.

By Werner Bresch; GvA

Figure 1: Mounting clamp for 50kN with leaf spring, indicator, pres-sure pad, isolator, semiconductor and heat sink

www.bodospower.com

The contact pressure must be capable of being applied reliably allow-

ing for all the tolerance values of the materials used in the clamping

assembly.

The materials used in the clamping assembly, especially pressure

distributors, insulators, thrust bearings and the contact surfaces of

the heat sinks must be plane-parallel.

The clamping system must be capable of applying the required con-

tact pressures in a reproducible manner.

The clamping system should ideally have a pressure indicator. This

simplifies the replacement of defective power semiconductors on site

considerably because the contact pressure adjustment can be repro-

duced again and again without using special tools.

Under-determined (e.g. only one tension bolt) and over-determined

(e.g. four tension bolts) clamping systems must not be used.

Note the length of the centering pins. They must be shorter than the

stud hole in the disc cell is deep.

Alternately tighten the nuts of the tension bolts maximum of ¼ turn.

Ensure the tension bolts and nuts have adequate tensile strength.

Use a fine pitch thread if required (recommended for disc cells > 3”).

The heat sinks used in the clamping assembly must have exactly

defined evennesses and roughness depths (approx. 10 μm) for the

contact surfaces to the disc cell. The use of a (ultra)-thin layer of

heat-conductive paste is recommended (please also refer to the next

section).

Heat-conductive paste, a never ending story

It must be noted here that the expression heat-conductive paste

defines an incorrect concept - this is because usage has its down-

sides. Applying too much (“a lot helps a lot”) considerably increases

the thermal resistance between power semiconductor and heat sinks.

Applying too little has the same effect. Both can result in thermal

overload as a result of poor heat dissipation. This fundamentally

applies to both the discrete and module design of power

semiconductors.

The ideal heat transfer between power semiconductor and cooling

unit would be a best possible adhesively joined, flat, metallic transi-

tion with a low roughness depth but without air inclusion. Such junc-

tion regions are not realisable in practise due to cost considerations.

For example, many modules with solder-contacted chips exhibit con-

vex module base plates – other design technologies such as pres-

sure-contacted modules exhibit convex/concave-shaped base plates

caused by the high tensile and pressure forces developed by the

internal clamping device. The heat sinks themselves are also not

perfectly even.

Figure 2: Mounting clamp schematic right and falsem

false assembly right assemblyfalse assembly right assembly

mounting clamp mounting clampmounting clamp g p

heat sink heat sink heat sinkheat sink heat sink heat sink

heat sinkh i k heat sinkheat sink

semiconductor semiconductorsemiconductor semiconductor

International Exhibitionwith Workshopson ElectromagneticCompatibility (EMC)15-17 March 2011Messe Stuttgart

EMV 2011Stuttgart

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This applies analogously for discrete power semiconductors in

screwed and flat base housings, as well as disc cells and plastic

moulded type power semiconductors.

So attaching power semiconductors to heat sinks inevitably results in

air inclusion. Air has a heat conductance up to 200 times lower than

a good heat-conductive paste. Applying heat-conductive paste should

therefore prevent air inclusion and ensure that the value for thermal

transfer resistance from power semiconductor housing to cooling unit,

specified in the data sheet, is attained.

The correct and reproducible application of heat-conductive paste

therefore takes on fundamental significance.

When using modules and discrete power semiconductors, different

heat-conductive pastes are deployed. For discrete power semicon-

ductors, heat dissipation and current are routed over the same inter-

face. Not suitable here are heat-conductive pastes optimised for

power semiconductor modules with electrically insulated base plate.

Suitable for discrete power semiconductors are heat-conductive

pastes such as Bechem Rhus or for modules, e.g. DC340 (Dow

Corning) or P12 (Wacker).

Note that all pastes must be free of impurities and foreign particles.

Old thickened or clumped heat-conductive pastes may not be used.

Heat-conductive pastes not completely used up must be disposed of

daily.

Applying heat-conductive paste is a science in itself. It can be applied

to the power semiconductor itself or to the heat sink. The best layer

thicknesses are between 30 μm and 100 μm depending on the filler

materials used in the heat-conductive pastes (e.g. graphite, silver,

zinc oxide). Which method is used for applying heat-conductive paste

essentially depends on the number of power semiconductors to be

assembled. It is important for all methods that the application is

reproducible so as to guarantee the same thermal transition resist-

ances from the housing of the power semiconductor to the cooling

unit.

Rolling on the heat-conductive paste:

This method is recommended for assembly of smaller to mid-sized

quantities. To prevent too high a level of fluctuation in layer thickness,

this process should only be performed by specially trained and expe-

rienced employees. A rubber roller is used to apply the heat-conduc-

tive paste to either the power semiconductor or the heat sink.

Manual application with screen-print or templates:

This method is suitable for medium to high quantities. The raster of

the screen/template broadly eliminates the risk of inhomogeneous

paste application and significantly improves reproducibility of the

application.

Automated application using a press:

When assembling high volumes, it is certainly wise to commit to the

costs accompanying such an investment. Process fluctuations are

broadly eliminated, manifesting itself in very good reproducibility of

the paste layer thickness.

Whichever method is used, it makes sense to check whether the

layer thickness of the heat-conductive pastes applied is correct. For

this, heat-conductive paste is applied to the power semiconductor as

described above. The power semiconductor is mounted onto the heat

sink with the nominal tightening torque or contact force. The entire

system should be allowed to settle for several hours and, if possible,

be subjected to several temperature changes (e.g. 25°K/100°K).

Afterwards the power semiconductor is removed carefully from the

cooling unit and the resulting print impression of the heat-conductive

paste assessed. If non-moistened contact areas can be seen on the

power semiconductor, the application was too thin. If the whole of the

contact area is moistened and the metal is shimmering through the

heat-conductive paste, the application is correct. If the contact sur-

face of the power semiconductor no longer shimmers through the

heat-conductive paste, the application is too thick.

Applying different heat-conductive paste layer thicknesses (starting

at, for example, 50 μìm in 10 μm increments) is the best way to

reach the optimum application. Layer thicknesses are best deter-

mined with “test combs”.

Data sheet values are spotlights

Not every value specified in the data sheet is explained and dis-

cussed at this point. Here it is more about the scenario in which

power semiconductors suddenly no longer work or are even defective

when operating in the same environment and application.


C O V E R S T O R Y

Figure 3: The thermal design influences the overall size

Figure 4: Heat-conductive paste applied with a screen-print

A manufacturer’s specification is the basis for every power semicon-

ductor data sheet. This specification may be a mirror image of the

data sheet. However, it may also be the case that, for political or

safety reasons, the values in the specification have a somewhat

stricter definition than in the data sheet. These are the “hidden

reserves” required by the power semiconductor to be able to demon-

strate an acceptable life expectancy.

These are not disclosed to users — the specifications in the data

sheet apply for them. It must also be noted that the specifications in

the data sheet only apply under the conditions stated therein. If these

conditions are different in the application, the data sheet specifica-

tions must be interpreted accordingly, and the reliability of operating

points must be supported by calculation using generally accepted

calculation methods.

Misinterpretation may result in the user operating power semiconduc-

tors, deliberately or unwittingly, in operational windows which are

possible given the physical properties of the power semiconductor,

but which are no longer substantiated by the data sheet.

Within a batch of power semiconductors slightly different values

occur for every parameter specified, which may be grouped closely

together under certain circumstances but can also be represented in

the form of a distribution curve. Records over multiple batches show

the entire breadth of the distribution of parameter values caused by

the production process.

If the design is within such a grey zone and the manufacturer

changes or optimises the process it may occur that the semiconduc-

tors of the next delivery conform to all the specification values and

data sheet values but still will not work in the application or even

become defective. The same applies when a competitive product is

to be used because of delivery difficulties.

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C O V E R S T O R Y

Figure 5: Heat-conductive paste applied on an IGBT module


In this context, the ignition current (Igt) of a thyristor is to serve as

the typical and ever recurring example. The ignition current specified

in the data sheet is a declaration stipulating simply that, under the

conditions specified, all manufactured thyristors must ignite (generally

at room temperature and at an anode-cathode voltage of 6 V and a

minimum ignition pulse duration of 20 μs). This means that the major-

ity of the thyristors can be ignited with ignition currents lying well

below the specifications in the data sheet. The basic conditions also

show that such an ignition current has little to do with application

conditions.

How a thyristor needs to be ignited under application conditions is

specified under di/dtcr. Usually required here is the fivefold of the Igt

value specified with an ignition current rise rate of 1A/μs and longer

ignition pulse widths/post-ignition pulses.

If, for cost reasons (weak ignition pulse levels are more cost-effec-

tive), a user assumes that all thyristors can be ignited well below the

Igt threshold, the following problems automatically arise:

Reliable ignition at low temperatures is not guaranteed: Malfunctions

may occur.

Reliable ignition with load current rises typical for the application is not

guaranteed: Long-term failures with so-called di/dt errors may occur.

Subsequently increasing the ignition current with the existing ignition

board is no longer possible in most cases.

Following process changes, the “new” thyristor may no longer be

capable of being ignited although the data sheet values are main-

tained.

The use of thyristors from alternative sources may not be possible

although they have the same, or even lower, Igt values.

The situation is similar when the application requires that power

semiconductors are operated in series or parallel connection. Here,

characteristics of the power semiconductor have to be used which

are not substantiated by the data sheet by default.

As long as the power semiconductors come from one batch, the vari-

ance of individual parameters required for the particular application

may be so low that series or parallel connection works. When, how-

ever, power semiconductors from different batches are used together,

the risk is extraordinarily high that failures will occur in the application

as a result of using power semiconductor characteristics not support-

ed by the data sheet.

Thermal design determines device dimensions

Arguably the most important issue in developing power electronic

stacks is thermal design because this essentially determines the

physical size of the system. By their very nature, the load currents

required in the application generate thermal power losses in the

power semiconductor that need to be dissipated via the heat sinks in

the form of heat loss. In principle, heat sinks may be self-ventilated,

separately ventilated or liquid-cooled.

The load currents occurring must of course be known so as to be

able to accurately determine losses, and hence the size of the cool-

ing unit and type of cooling. Overload conditions in regard to magni-

tude and time must be known just as much as load values for under-

voltage operation.

It is equally important to know how and under which operational con-

ditions the power electronic devices are deployed. Power electronic

stacks which are subjected to high, rapid step changes in load must

have an altogether different thermal design compared to power elec-

tronic devices running continually with minor load changes for days

on end. The mechanic design of the selected power semiconductor

and its associated long-term operational behaviour play a key role

here.

In combination with the circumstances given above, it is sensible to

ensure that power semiconductors from different manufacturers can

also be deployed as an alternative to avoid single source situations.

All of these facts must be taken into consideration in the final thermal

design. The thermal design may well be inadequate if load require-

ments are not specified correctly, operating conditions are not

assessed correctly or if power semiconductors are not selected

properly.

Quite often, designs can be found, which have to make use of the

hidden reserves to cope with critical load conditions or the users

hope that not all worst case scenarios will coincide. The power semi-

conductor is then operated in the critical grey areas already

described above.

Subsequent optimisation of these kinds of designs is usually associat-

ed with major overhead and is often not possible for mechanical rea-

sons, often resulting in exotic attempts to rectify the problem - such as

gilding the contact surfaces of the power semiconductors used.

Long-term properties and reliability - in-built reserves make the

difference

The belief that power semiconductors are non-wearing and non-age-

ing is not correct in this sense. For example, the silicon integrated in

the power semiconductor reacts to different voltage loads. Therefore,

a permanently applied DC voltage clearly stresses the silicon more

than an AC voltage of the same magnitude. Also, given the high-

energy cosmic radiation, the risk of damage to the silicon is greater

the more the silicon is loaded in terms of voltage. With appropriate

reserves in the voltage design, these risks are easily controlled and

minimised provided they are taken into consideration in the develop-

ment phase. Power semiconductor manufacturers regularly conduct

reliability tests in the form of voltage stress tests to verify the long-

term voltage stability of power semiconductors. For this purpose, DC

or AC voltages are applied to the power semiconductors over speci-

fied time periods and at defined temperatures. The leackage current

is also logged in parallel and should show values which are as stable

as possible.

As described previously, power semiconductors are made up of a mix

of materials. This mix has already been described for the disc cells.

For modules, the base is often a copper base plate and the silicon

sits on copper-coated insulator ceramic. A differentiation is made

between solder-contacted and pressure-contacted module technolo-

gies. For IGBT modules, there is an additional technological weak

point: chip-bond contacting.

If this mix of materials is heated cyclically with alternate loading, the

different materials will expand differently. The junction areas are

stressed, the thermal transition resistances start to rise and the trans-

fer reserves and the reserves in blocking behaviour are slowly wast-

ed. Then, sure enough, the power semiconductor fails as a result of

ageing.

C O V E R S T O R Y

Different life expectancies can be assumed for different design tech-

nologies.

Over the same temperature range, several tens of thousands of such

load cycles can be expected for TO247 and isotope housings, for

IGBT modules, several hundred thousand depending on design and

several millions for disc parts.

Power semiconductor manufacturers verify and document this load

cycle stability with appropriate reliability testing.

This information is of enormous importance when designing power

electronic stacks. Whilst a fan drive can have a life expectancy of

years for a specific load and the resulting defined temperature range,

the same drive used as a lift drive operating under the same loads

will have a life expectancy of just a few weeks.

If the application demands these frequent load cycles and the power

rating may not be reduced, the temperature range must be reduced

to attain the prolonged service life required. This can only be

achieved with over-dimensioning of the power semiconductor com-

pared to the power rating required. This can be realised only if there

is sufficient room for improved cooling and larger IGBT modules.

Actuation of bipolar power semiconductors - “power” is every-

thing!

Bipolar power semiconductors are controlled by current. This requires

a powerful trigger circuit to be able to provide the required ignition

current. The risks of inadequate ignition are addressed in the previ-

ous section.

In practise, there are many drives with poor design that do not meet

the minimum requirements. A supply voltage that is too low is often

selected (12 V is borderline here). The same applies for the power

supply provided.

This narrows down any potentially necessary optimisation options or

for very unfortunate scenarios averts the use of possible alternatives

in the event of supply bottlenecks because they may require a higher

ignition current.

With a supply voltage of e.g. 24 V, a powerful power supply protected

against short-circuit current and an ignition pulse transformer capable

of transferring strong ignition pulses with ignition times of 250 μs with

a repetition rate of approx. 2 kHz, the design is on the safe side and

all of the problems described above are averted.

Activating Bi-Mos power semiconductors – control power

desired!

Bi-Mos power semiconductors are voltage-controlled. Applying a pos-

itive control voltage of 15 V turns it on; removing the control voltage

switches it off. Activation is very simple and requires practically no

power. This is more or less how it is portrayed in technical literature.

Such an activation design must of course not cost much, something

reflected in many driver board designs.

In reality, the design of a driver board is the technical crux in the

overall design of an inverter, is very complex and anything but sim-

ple. No other power semiconductors reflect design errors in the driver

board so strongly into the overall design than IGBTs.

There are quite a lot of driver boards where only 12 to 13V of the

control voltage reach the gate of the IGBT at rated supply voltage or

the power supply units become hot at the required switching frequen-

cy because large IGBTs in particular require significant levels of

power or for which it is not possible to momentarily deliver relatively

high current peaks (a few A to 10 A depending on application) to the

gate for specific adjustments and the minimisation of switching loss-

es. Such driver board designs do not allow anymore leeway in order

to take corrective action in view of switching loss optimisation, con-

trolling overcurrent and short-circuit current cut-off.

The only solution here is a complete redesign.

This redesign, which is tailored to the IGBT size selected, should be

as follows:

• Reliable gate voltage supply with +/- 15 V, even for supply under-

voltage

• Design of the power supply unit in line with power rating

• High pulse current capability for the possibility of hard switching

loss optimised gate control

• High dv/dt immunity

• Low coupling capacity

• General-purpose usage for IGBTs of the same size, but from

different suppliers.

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C O V E R S T O R Y


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26

P O W E R M O D U L E S


Wind power generation is being steadily employed all over the world,

particularly in Asia and the USA, with offshore applications playing an

increasingly important role. What good are the perfect location and

high wind speeds, however, if the power generation system does not

feature properly matched components. SKiiP Intelligent Power Mod-

ules are optimised for use in wind power units. What’s more, Semi-

kron`s broad expertise in this field guarantees customers extensive

design support. An integrated approach and flexibility in thinking –

these unique capabilities are what enables this global player to meet

the ever increasing demands that the move towards full-size power

conversion systems in wind power applications results in for compo-

nents and applications: higher currents, parallel operation and more

effective cooling.

Around 80 percent of the wind power units featuring electronic control

systems installed worldwide now use a doubly-fed asynchronous

machine which is fed by an inverter via the rotor current. The major

advantage of this machine is that it only has to be designed for

around 20 percent of the rated output of the WPU, since 80 percent

of the power is generated in the stator winding, which is directly con-

nected to the grid. One shortcoming here, however, is the high-main-

tenance slip ring contacts and the indirect control (system). In the

event of grid disturbances, very high rotor current are needed to keep

the grid stable in such difficult situations.

Technological progress is one of the main reasons why regenerative

energy is not only used in addition to conventional energy generation

means, but is in fact increasingly replacing it. Especially in countries

where energy demand is high, recent years have seen the launch of

wind farms that are as large as 35 km2. In order to guarantee grid

stability, the requirements with regard to reactive power supply and

grid stability in the case of grid voltage dips have become increasing-

ly tight. For this reason, when new WPU’s are being installed, syn-

chronous or asynchronous generators with full-size converters are

increasingly being used, because they support the grid in the event

of power outage. The inverter is directly controllable, provides opti-

mum synchronisation to grid frequency of 50 or 60 Hz, and can both

compensate harmonic reactive power and produce reactive power

compensation. In addition, synchronous generators can feature a

large number of many poles (>50), making gears in the drive part,

which was one of the most common causes or malfunction in the

past, superfluous.

In inverters used in all kinds of systems, a rated voltage of 690 V is

commonly used for reasons of economy, as well as to achieve opti-

mum efficiency. A common type of power converter comprises IGBTs

with a blocking voltage of 1700 V; a transformer is used for power

adjustment to the 20 kV grid. Far more costly 3.3-kV modules are

barely used because here, too, the system requires transformers,

making the overall solution too expensive.

More power, more power electronics

Wind turbines are being designed to cover an increasingly larger

power range, although the location is the all-important factor for the

output. In onshore wind turbines 3 MW turbines have proven to be

most economic, while offshore wind farms with an output of 5 MWs

and above are the better solution. If both types of wind power unit

– doubly-fed asynchronous machine and synchronous/asynchronous

generator with a full-size converter – are to be able to provide the

same output, the power of the full-size converter has to be five times

higher. This in turn means that five times the power electronics is

needed. As, however, the low output frequencies of doubly-fed asyn-

chronous machines have to be taken into account, this is normally

reduced to an increase by a factor of 3 – 3.5.

Making Making WWindindWind turbines are being designed to cover

an increasingly larger power range

Wind turbines featuring power electronics are becoming increasingly popular all over the world. Semikron provides application-specific solutions combining power

electronics with customer support.

By Rainer Weiß, Application Manager and Ralf Herrmann, Product Manager at Semikron

Figure 1: Different climatic requirements exist, depending on theintended location of the WPU. For instance, the extreme climate con-ditions in China and Mongolia are somewhat conflicting as regardstemperature and relative humidity, which is why the power electronicssystem used here has to be adapted to meet these very requirements.

Power electronics is not only becoming increasingly popular, howev-

er. In fact, the requirements they have to meet are changing con-

stantly, too. Owing to the fact that in doubly-fed asynchronous

machines the semiconductor heats up differently at low temperatures,

the protective mechanism has to be adapted to be able to deal with

this. Extreme climatic conditions are a further cause of new and

changing demands that components have to meet. Off-shore wind

turbines are subjected to high humidity levels, while wind power units

in Texas, for instance, are exposed to elevated temperatures. Conse-

quently, the cooling systems used have to be designed differently. It

is therefore important that the development of cooling solutions for

individual applications be based on an extensive pool of experience.

The right know-how to combat common prob-

lems

The efficiency of an inverter lies at between 98 and

99 percent. A 6 MW full-size converter will there-

fore display losses of around 100 kW. The heat

produced in these compact systems proves to be a

major problem for the electronic components in

terms of cooling. If the coolant is too cold, this will

cause condensation to form with the coolant con-

densing on the heatsink. This must be taken into

account, especially in regions with high humidity

levels.

A further challenge is the overvoltage that occurs

during commutation of the huge currents. As mod-

ules designed for currents of 500A and above have

a relatively large spatial expansion, their stray

inductances are not negligible. To combat these

two problems not only is an intelligent, well thought

through cooling concept needed, but also an opti-

mum DC link design. Expertise, experience and

optimised application-specific modules which help

fully exploit the power of the wind are needed to

ensure that minimum effort is called for to meet the

requirements of operators of WPUs.

Of the WPUs installed worldwide by the end of

2009, totalling an output of 122 GW, 57 GW fea-

ture solutions developed by Semikron. The wealth

of experience in the wind power sector that the

power electronics market leader has built up over

the years does not, however, stop at the mere sup-

ply of IPM modules. In fact, Semikron is also

actively involved in the design of new WPUs,

where the company’s experience and synergy

effects are highly beneficial. Consultation in the

area of system protection, for example overcurrent

or overvoltage protection, are also part and parcel

of the Semikron service portfolio. Semikron also

manufactures inverter subsystems, which is why

the developer of modules for WPU’s boasts consid-

erable expertise in the area of individual compo-

nent dimensioning. This know-how is important for

the manufacturers of inverters, as it helps them

configure the DC link circuit properly, so as to

ensure that this not only meets the application

specifications, but also achieves a prolonged serv-

ice life.

Improvements in design and packaging technology

Different locations mean different requirements and problems. This is

something Semikron is very aware of and has factored in to the

improvement of its IPMs. The SKiiP family is already in its 4th gener-

ation. Maximum reliability and prolonged service life in compact

designs is top priority in wind turbines, especially because system

maintenance is costly and complex, and results in financial loss due

to loss of income during downtimes where no electrical energy is pro-

duced. Reliability throughout the WPU’s minimum service life of 20

years is down to the SKiiP modules and their reliable high quality

packaging technology. This is an important merit, especially given the

increasing tendency towards offshore wind farms.

27


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Thanks to the optimum chip distribution on the insulating substrate

(DCB), the low-inductance module design and symmetric current dis-

tribution, the power density of SKiiP modules is around 20 times that

of competitor products. All SKiiP modules come as a unit comprising

heat sink, power electronics and gate drivers. Customers have two

standard heat sinks to choose from, or may opt for a custom-devel-

oped heat sink solution.

Growth and full-size converters are the key trends

Wind turbines featuring power electronics are becoming increasingly

popular all over the world. China and the USA, for example, rely

heavily on wind power to meet ever increasing energy demands. In

countries with attractive energy subsidy schemes, a clear increase in

the number of wind turbines can be seen.

Another clear trend is the move away from doubly-fed asynchronous

machines towards full-size converters, as the latter allow more easily

for operator requirements to be met and grid quality to be increased.

Semikron is fully aware of all of these challenges and requirements,

boasting years of experience in the wind power sector. Power elec-

tronics market leader Semikron produces power electronic products

for the wind power sector, designs and manufactures its own prod-

ucts, and offers development support to its customers. For 20 years,

Semikron has contributed to all-important synergy effects resulting

from its cooperation with leading wind turbine manufacturers. Semi-

kron plays a key role in wind power generation and will continue to

do so in the future.

Both the increase in the number of wind turbines and the trend

towards full-size converters has led to an increase in demand for

power electronics. With its innovative products, Semikron considers

itself well equipped to deal with the resulting new challenges, setting

new standards in wind power technology.

www.semikron.com


Figure 2: 88% of the total 1,471 MW of offshore wind power (as per2008) is generated using SKiiP modules (Source: http://www.renew-ableenergyworld.com)

Figure 3: SKiiP 4, maximum reliability and prolonged service life incompact designs

Figure 4: In comparison to standard leaded modules with base plate,SKiiP 4 IPM has a 7,5 times higher temperature cycling capability.


The soft switching is the representative feature of resonant convert-

ers. [1] [2]. But the use of the body diode in resonant converters

sometimes leads to the system failures. The stored charge in body

diode should be completely removed to avoid high current and volt-

age spikes including high dv/dt and di/dt in these topologies. There-

fore, critical parameters of power MOSFETs such as Coss(er), Qrr

and reverse recovery dv/dt directly affect to dynamic performance of

resonant converters The new power MOSFET, called UniFET II

MOSFET is optimized for resonant converters. It provides better reli-

ability and higher efficiency in resonant converters.

Reliability on resonant converters

Several topologies as a DC-DC converter for server and telecom

power supplies have been introduced to reduce switching losses,

device stresses on the power MOSFETs and the radio frequency

interference(RFI) while achieving high power density. Among them,

resonant converters which utilize body diode of MOSFETs for zero

voltage switching are very suitable for these applications. Especially,

the phase-shifted ZVS full-bridge converters have been widely

accepted for high-end power supplies since it allows all switches to

operate at ZVS by effective Coss of power MOSFETs and leakage

inductance of transformer without additional auxiliary switch. Howev-

er, ZVS range is very narrow and the freewheeling current consumes

high circulating energy. In the late 1990s, power MOSFET failures

have been reported in the phase-shifted ZVS full-bridge topology.

The one the root cause of failure is slow reverse recovery of the body

diode by low reverse voltage. The other failure is due to the Cdv/dt

shoot-through at no or light load conditions [3][4]. These kinds of fail-

ures are not happening in LLC resonant converters because LLC

resonant converter can guarantee ZVS operation at even no load.

LLC resonant converter can achieve high efficiency at high input volt-

age and low voltage stress on secondary rectifier since there is no

inductor on secondary. Because of these unique characteristics, LLC

resonant converters are becoming a popular topology for many appli-

cations especially from server and telecom power supplies even to

low profile flat panel display TV power supplies. A block diagram of

LLC resonant converter is shown in figure 1. Figure 2 shows typical

waveforms of its zero voltage switching. Conduction periods of Q1

and Q2 should not overlap to guarantee proper operation of the con-

M O S F E T

UniFETTM II Optimized Power MOSFETs

for Resonant ConvertersWith reduced gate charge and stored energy in output capacitance,

switching efficiency is increased

Resonant converters are one of the most exciting power supply topology. These convertersare very popular for many applications since its performance delivers increased powerefficiency, minimized components count and reduced EMI over previous power supply

topologies.

By Wonsuk Choi, Sungmo Young and Denny Kim Fairchild Korea Semiconductor, HVPCIA, PSS Team, Bucheon-si, Republic of Korea

Figure 1: LLC Resonant Converter

Figure 2: Zero Voltage Switching in Resonant Converter

verter. A dead time must be introduced to prevent simultaneous con-

duction of the MOSFETs. As shown in figure 2, during this delay time,

current flow through body diode of the each MOSFET to guarantee

ZVS operation. The ZVS is achieved with magnetizing current, which

is not related to load current, so ZVS could be realized even with

zero-load and the voltage across the MOSFET is the forward voltage

of the body diode which can be negligible. When other MOSFET

turns on, the body diode naturally turns off, resulting in no reverse

recovery losses. Therefore, fast recovery MOSFET is not necessary

in normal ZVS operation. However, MOSFET failures in LLC reso-

nant converters are associated with shoot through current due to

poor reverse recovery characteristics of the body diode at start-up

state. Figure 3 shows the first five switching waveforms of the power

MOSFET at startup. Just before startup of the converter, resonant

capacitance and output capacitance are completely discharged.

These empty capacitances cause further conduction of the body

diode of low-side MOSFET during startup compared to normal opera-

tion conditions. As a result, reverse recovery current, which flows

through body diode of low side MOSFET is much higher, and is

enough to make shoot-through problems when the high-side MOS-

FET is turned on [5].

And another field failure was found at specific conditions such as

over-load or short-circuit condition in the LLC resonant converter [6].

Even though voltage and current of power MOSFETs are within safe

operating area, some unexpected failures associated with shoot

through current, reverse recovery dv/dt, and breakdown dv/dt happen

in various conditions, such as over load and output short circuit. Fig-

ure 4 shows how an operating point moves during overload and

short-circuit condition. As shown in figure 4, DC gain characteristics

of LLC resonant converter is classified into tree region according to

different operating frequency and load condition. The right side (blue

box) of resonant frequency, Fr1 is ZVS region and the left side (red

box) of minimum second resonant frequency, Fr2 at no load is ZCS

region. The region between Fr1 and Fr2 can be either ZVS or ZCS

region according to load condition. The converter operates with ZVS

in normal operation, but the operating point moves to the ZCS region

under overload condition or short circuit condition and the character-

istics of series resonant converter become dominant. During overload

condition or short circuit condition, the switch current is increased

and ZVS is lost. Lm is fully shorted by a reflected load, RLOAD, at

overload condition. This condition usually results in ZCS operation.

The most severe drawback of ZCS operation (below resonance) is

hard switching at turn-on lead to the diode reverse-recovery stress.

Furthermore, switching loss increases at turn on and noise or EMI is

generated. The diode turns off at a very large dv/dt and therefore, at

a very large di/dt, generates a high reverse-recovery current spike.

These spikes can be over ten times higher than the magnitude of the

steady-state switch current. This high current causes considerable

increase in losses and heats up the MOSFET. Then, an increase in

junction temperature degrades dv/dt capability of MOSFET. In

extreme cases, it may destroy the MOSFET and cause system fail-

ure. In specific applications, load conditions are suddenly changed

from no load to over-load and more rugged operating is required for

system reliability [7][8].

The worst case is a short-circuit condition. During short circuit, the

MOSFET conducts extremely high (theoretically unlimited) current

and frequency is reduced. When short circuit occurs, Lm is shunted

in resonance. LLC resonant converter can be simplified as a series

resonant tank by Cr and Lr because Cr resonates with only Lr. Opera-

tion mode during short circuit is almost same as overload condition,

but short-circuit condition is worse because reverse-recovery current,

which flows through the body diode of the switch, is much higher.

Figure 5. shows the switching waveforms of the power MOSFETs at

short circuit condition. Waveforms during short circuit are similar to

those during overload condition, but the current level during short-cir-

cuit condition is much higher and can lead to increased junction tem-

perature of MOSFET and make it easier to fail.

MOSFET Failure Mechanism

As shown in figure 6, there is a little resistance described as Rb.

Basically, base and emitter of parasitic BJT are shorted together by

source metal. Therefore, the parasitic BJT should not be activated. In

practice, however, the small resistance works as base resistance.

When large current flows through Rb, a voltage across Rb that acts

as base-emitter forward bias becomes high enough to trigger the par-

asitic BJT. Once the parasitic BJT turns on, a hot spot is formed and

more current crowds into it. More current flows through it due to neg-


Figure 3: Waveforms of Power MOSFETs at Startup

Figure 4: Operating Points of LLC Resonant Converter According toLoad Condition

Figure 5: Waveforms of Power MOSFETs at Short-Circuit Condition

M O S F E T


ative temperature coefficient of the BJT. Finally, device fails. Another

failure mode is breakdown dv/dt. It is a combination of breakdown

and static dv/dt. A device undergoes avalanche current and displace-

ment current at same time. In case of extremely fast transition, drain-

source voltage may exceed maximum rating of a device during body

diode reverse recovery process. If the MOSFET enters the break-

down mode due to high voltage spikes, commutating current flows

through P-N junction. It is exactly same mechanism to avalanche

breakdown. In addition to this process, high dv/dt affects failure point

of device. More displacement current is built up with greater dv/dt.

The displacement current is added to avalanche current, and device

becomes more vulnerable to failure. Basically, the root cause of fail-

ure is parasitic BJT turn-on due to high current and temperature. But,

the primary cause is different; body diode reverse recovery or break-

down. In practice, these two failure modes happen randomly, and in

combined way sometimes.

UniFETTM II MOSFET Technology

The body diode of power MOSFETs has very long reverse recovery

time and large reverse recovery charge. In spite of its poor perform-

ance, the body diode has been utilized as freewheeling diode

because it can make simple circuit without adding system cost in

some applications such as resonant converters. As more and more

applications use an intrinsic body diode as the critical component in

the system, body diode characteristics have been developed. Fast

recovery MOSFET is good choice for reliability on resonant convert-

ers. However, there are drawbacks due to the processes. More life-

time control results in the further increase of MOSFET on-resistance.

This will add more conduction loss and is very critical to the resonant

converter. Another negative effect is the increase of drain-source

leakage current. Also manufacturing cost has increased due to addi-

tional process for life time control. For better Rds(on) and cost,

Fairchild designed a new highly optimized power MOSFET, called

UniFET II MOSFET, for resonant converters with deep analysis of

MOSFET failure mechanisms. It has improved body diode rugged-

ness and output stored energy in Coss while minimize negative

effects. Its peak reverse recovery current has been reduced to the

level that does not causes device failure without increase in on-

resistance. It can also withstand more than double the current stress

Figure 6: MOSFET equivalent circuit

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during breakdown dv/dt mode. As shown in table 1 and figure 7, the

reverse recovery charge of UniFET II MOSFET is dramatically

reduced by 50% and 88% compared to competitors part.

MOSFET’s capacitance is nonlinear and depends on the drain-

source voltage since its capacitance is essentially a junction capaci-

tance. In soft switching applications, MOSFET output capacitance

can be used as a resonant component. When the MOSFET is turned

on, the current that extracted from the magnetizing energy stored in

transformer flows to discharge the MOSFET output capacitance in

order to allow ZVS condition. Therefore, if stored energy in output

capacitance of MOSFET is small, less resonant energy required to

achieve soft switching without increasing the circulating energy. The

UniFET II MOSFET has approximately 35% reduced stored energy in

output capacitance than same on-resistance competitor’s devices at

for typical switching power supply bulk capacitor voltage. The bench-

mark of stored energy in output capacitance is shown in figure 8.

The switching process of the diode from on state to reverse blocking

state is called reverse recovery

Firstly, the body diode was forward-conducted for a while. During this

period, charges are stored in the P-N junction of the diode. When

reverse voltage is applied across the diode, stored charge should be

removed to go back to blocking state. The removal of the stored

charge occurs via two phenomena: the flow of a large reverse current

and recombination. A large reverse recovery current occurs in the

diode during the process. This reverse recovery current flows through

the body diode of MOSFET because the channel is already closed.

Some of reverse recovery current flows right underneath N+ source.

Figure 9 shows MOSFET failing waveforms during body diode

reverse recovery. With competitor A, failure happens right after the

current level reaches Irm, peak reverse recovery current at 6.87V/ns.

It means the peak current triggered parasitic BJT. But UniFET II

MOSFET was not failed at even more higher dv/dt, 14.32V/ns.

Application Benefit

Figure 9 presents waveforms comparing reverse recovery character-

istics at short circuit between the competitive device and UniFET II

MOSFET. Operation mode is changed form ZVS to ZCS after output

short. A peak drain-source voltage of the conventional MOSFET

exceeded rated voltage (500V), and current spike is several tens of

ampere current due to large Qrr. MOSFET to be switched on carries

reverse recovery current of the other MOSFET. On the contrary, cur-

rent spike of UniFET II MOSFET is relatively lower due to much

smaller Qrr on ZCS operation during output short, and device was

not failed. The other failure case can be happened during start-up

state. Figure 10 presents key waveforms comparing reverse recovery

characteristics at start-up between the competitor MOSFET and

UniFET II MOSFET. With the competitor MOSFET, high level of

shoot-through current, exceeded 27.6A, is induced due to higher Irm

of body diode. Consequently, it triggered a protection function of con-

trol IC. On the contrary, low peak current spike happened with the

UniFET II MOSFET.

These negative behaviors of the MOSFET may result in device fail-

ure as mentioned; reverse recovery dv/dt and breakdown dv/dt.

Finally, the UniFET II MOSFET can effectively minimize shoot-

through current, peak drain-source voltage, and reverse recovery

dv/dt which can be potential causes of failure at start-up state, over

load and short circuit condition. In order to compare the efficiency of

M O S F E T


Figure 7: Reverse recovery performances comparisons

Figure 8: Stored energy in output capacitance

Table 1: Critical Specification Comparison of DUTs

Figure 9. Waveforms of Power MOSFETs at short circuit condition

a UniFET II MOSFET and competitors, a 240W LLC resonant half-

bridge converter is designed. An input voltage is 110-220Vac and out-

put voltage and current have set to 12V and 20A, respectively. A syn-

chronous rectification is used for secondary side. The summary of

the efficiency measurements is shown in figure. 11. Efficiency

increases about 0.5% compared to competitor MOSFETs at heavy

load condition. The major reason for higher efficiency is the reduced

switch-off loss and output capacitive loss because of lower Qg and

Eoss.

Fairchild has announced a new power MOSFETs family, called

UniFETTM II which combine a faster and rugged intrinsic body diode

performance with fast switching, aimed at achieving better reliability

and efficiency on applications, including resonant converter. With

reduced gate charge and stored energy in output capacitance,

switching efficiency is increased and driving and output capacitive

losses are decreased. These performances of UniFET II MOSFET

provide designers to significantly increase system reliability particu-

larly on resonant converters.

References

[1] N.Mohan, T.M.Undeland and W.P.Robbins, “Power Electronics,

converters, applications, and design”, John Wiley & Son, Inc.,

New York 1995, 2nd Edition.

[2] R. Farrington, M. M. Jovanovic, and F. C. Lee, “Analysis of Reac-

tive Power in Resonant Converters,” Proc. IEEE PESC ’92, 1992.

[3] Hubert Aigner. Et al., “Improving the Full-Bridge Phase-shift ZVT

Converter for Failure-Free Operation Under Extream Conditions in

Welding and Similar Applications,” IEEE Proceedings of Industrial

Application Society Annual Meeting. St. Luis, 1998.

[4] Sampat Shekhawat, Mark Rinehimer, Bob Brokway, “FCS Fast

Body Diode MOSFET for Phase-Shifted ZVS Full Bridge DC/DC

Converter,” Fairchild Application Note AN-7536.

[5] Wonsuk Choi and Sungmo Young, “Improving System Reliability

Using FRFET® in LLC Resonant Converters,” PESC 2008, June

2008.

[6] Wonsuk Choi, Sungmo Young, Dongwook Kim, “Analysis of MOS-

FET Failure Modes in LLC Resonant Converter,” INTELEC 2009,

October 2009.

[7] Hangseok Choi, “Analysis and Design of LLC Resonant Converter

with Integrated Transformer,” APEC 2007, Feb. 2007.

[8] Bo Yang, F. C. Lee, and Concannon, “Over-Current Protection

Methods for LLC Resonant Converter,” APEC 2003, Feb. 2003.

www.Fairchildsemi.com

M O S F E T


Figure 10. Waveforms comparisons at start-up state

Figure 11: Efficiency comparisons on LLC resonant converter

Figure 9: Voltage and current waveforms during reverse recovery ofbody diode

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IGBTs have many designs, but typically the power ICs are attached

to a highly thermally conductive ceramic which bears the copper

traces. The bottom side of the substrate is bonded by solder or

another adhesive to a metal or composite heat sink. After assembly

of the IGBT, a critical performance detail is the integrity of the solder

bond between the substrate and the heat sink. Voids in the solder,

delaminations along either solder interface, or uneven solder thick-

ness can significantly reduce or modify heat flow across the interface

and cause the unit to overheat and fail.

A similar heat dissipation requirement exists in flip chips used as

high-performance microprocessors that are bonded to a more mod-

est heat sink by an adhesive or an electronic grease whose thick-

ness must be within specified values and which must be free from

voids. IGBTs have far more heat to be dissipated, but the require-

ments for adhesive thickness and integrity are roughly similar.

Sonoscan’s applications laboratories have seen increasing numbers

of IGBTs used in diverse applications in recent years.

The inverted cross-section in Figure 1 shows the normal arrange-

ment for acoustic imaging of the solder adhesive, where the ultrason-

ic transducer raster-scans the heat sink surface. This figure shows

what may happen to thermal energy that flows from the ICs of an

IGBT and encounters the solder between the ceramic and the metal

heat sink. Thermal energy travels by two modes, conduction and

radiation. If the ceramic and the heat sink are well bonded by the

solder layer (at left in Figure 1), heat will flow efficiently across the

interface and the IGBT will not overheat. But there may be a gap at

the interface - “gap” meaning a void within the solder or the separa-

tion of the solder from either surface. When thermal energy reaches

the interface between the ceramic (a solid material) and the gap (a

gas such as air, or a vacuum), heat transfer by conduction ceases

(Figure 2). Heat transfer by radiation continues but is reduced by

orders of magnitude by the gap. The gap is a good thermal insulator.

Thermal energy that does not cross the gap is reflected back toward

the ICs. If the combined area of gaps is large enough, the IGBT will

overheat and fail. It may also overheat and fail in the absence of

gaps if there is sufficient variation in the thickness of the solder adhe-

sive In this case, removal of heat takes place unevenly across the

area of the ceramic. As a result, hot spots may develop on the die.

Examining the interface between the heat sink and the ceramic non-

destructively with an acoustic microscope is preferable to destructive

methods, which would leave the IGBT in pieces and which would

probably reveal the condition of the interface only at a few spots.

The value of acoustic microscopy is that ultrasound is reflected only

from interfaces between materials, whether the interfaces are two

solids or a solid and a gap.

In practice, the transducer of the acoustic microscope raster-scans

the metal heat sink at the bottom side of the IGBT. Several thou-

sand times a second, ultrasound at a selected frequency (typically 30

M E A S U R E M E N T


Acoustic Imaging for IGBT Reliability

Uneven solder thickness can allow localized overheating

Insulated Gate Bipolar Transistors, or IGBTs, are widely used in, trains, elevators, windmills and many other applications where robust high-power switching is required.Not surprisingly, IGBTs generate considerable heat in operation, and the heat must be

efficiently dissipated to prevent the IGBT from overheating and failing electrically. Preventing electrical failure is especially important in critical IGBT applications such as

high-power switching on military aircraft.

By Tom Adams, Consultant, Sonoscan, Inc

Figure 1: The effect of a gap on heat transfer through solid materials

Figure 2: The solid-to-gap interface reflects virtually all of the ultra-sound


MHz or 50 MHz) is pulsed into the IGBT and

the return echo signals are collected by the

transducer. Ordinarily in acoustic imaging

only the return echo signals from a depth of

interest are used to make the acoustic

image; signals from other depths are dis-

carded. The return echo signals are said to

be gated on the desired depth, with both a

start point and a stop point, each expressed

in nanoseconds. In the case of an IGBT

being scanned along the heat sink surface,

the depth of interest includes the solder and

its interfaces with the ceramic and the heat

sink.

If the two solid materials are well bonded,

the portion of ultrasonic energy reflected at

the interface can be calculated by knowing

the density and acoustic velocity of each

material. But if there is a gap,, the ultra-

sound will encounter the interface between a

solid and a space, and virtually all of the

ultrasound will be reflected back to the trans-

ducer [Figure 2]. The very high amplitude

return echo signal from the solid-gap inter-

face will appear as bright white pixels in the

acoustic image, while solid-to-solid inter-

faces will be some shade of gray. (Where

two identical materials are truly bonded, as

in direct-bonded silicon wafers, no ultra-

sound is reflected and the pixels are black.)

Figure 3 is the acoustic image of a 9-die

IGBT, made from the return echo signals

reflected from the depth between the metal

heat sink and the substrate. The heat sink

covers all nine ceramic substrates, which are

in turned bonded to the nine die that are

deeper than the depth of interest displayed

in this image. Ideally, all of the ceramic sub-

strates would have the same medium-gray

color, but this acoustic image immediately

makes it clear that conditions at the interface

are not ideal.

A closer look at the acoustic image of the

IGBT at top center is shown in Figure 4..

The scattered small white areas are voids in

the solder between the ceramic and the heat

sink. As shown in Figures 1 and 2, the voids

block both heat and ultrasound. Such voids

are not unusual, but these voids are too

small to have much impact on overall heat

transfer.

The bond region itself grades from dark grey

to lighter grey to white. This is an unusual

acoustic image - a subtle gradation from

dark grey to light grey would be more usual.

What could cause such an unusual acoustic

image?

One anomaly that is fairly frequent in IGBTs

is warping and tilting of the ceramic sub-

strates. The larger, thicker metal heat sink

remains flat, so the warping of the ceramic

causes local changes in the thickness of the

solder. The thickness changes are very

slight but become visible in acoustic images.

The upper left and right corners of Figure 4

appear white because the solder here is so

thin that the ultrasonic echoes returning from

the top and bottom sides of the solder are so

close together in time that the two echoes

merge in what is called constructive interfer-

ence. Here, constructive interference

appears white.

As the solder gradually becomes thicker,

interference ceases fairly abruptly and the

solder appears medium grey. Eventually the

solder reaches a thickness that again caus-

es interference, visible where medium grey

shifts abruptly to dark gray.

As mentioned earlier, uneven solder thick-

ness can allow localized overheating of the

die. Similarly, the electronic grease attaching

a heat sink to a flip chip must have a thick-

ness that is between perhaps 30 and 90

microns. An electronic grease thickness out-

side of this range anywhere in the bond can

cause overheating. Deformation and tilting of

the ceramic layer that causes the solder

thickness to vary is a fairly common problem

in IGBTs.

Figure 5 shows an array of six IGBTs. The

raster-scanned planar acoustic image is

shown at the top of Figure 5. The six IGBTs

contain numerous small white voids, large

delaminations (#2 and #4) and areas where

the solder is too thin (#6). To learn more

about the internal condition of the array, a

non-destructive acoustic cross section,

patented by Sonoscan and called Q-BAM™,

was made. The horizontal green line shown

in Figure 5 was selected as the vertical slice

location, and this line was scanned multiple

times at increasing depths to gather the

data. The resulting non-destructive Q-BAM

cross section is shown in the lower part of

Figure 5.

Two key features in the cross section are the

horizontal lines that mark the top and bottom

of the solder layer. In this image the heat

sink is at the top, and the ceramic layers are

below the solder. It is easy to see that

some of the ceramic pieces are tilted. Yellow

arrows mark some of the voids that lie along

the green line and that are in contact with

the ceramic or the heat sink. The legend in

the Q-BAM image relates ultrasonic travel

time to distance, and the ten division mark-

ers at the left show that the vertical extent of

the array shown here is slightly more than 3

mm. The features near the bottom of Figure

5 are the die and associated bond wires.

Some of the IGBTs imaged by Sonoscan are

from development or production environ-

ments, but many are field failures where it is

desirable to determine the root cause of the

failure. Some failed IGBTs look acoustically

similar to the images shown here. But some

of the IGBTs arriving at a Sonoscan lab have

clearly exploded - much of the mold com-

pound has been blown off, and the die is

often in fragments. Still, if the ceramic and

heat sink are intact, it may be possible to

image the wreckage from the back side to

determine whether voids or other defects are

present. Some anomalies might, of course,

have been caused by the explosion.

www.sonoscan.com

M E A S U R E M E N T

Figure 3: Acoustic image of the solder bondbetween the ceramic layer and the heat sinkin a 9-die IGBT

Figure 4: Thickness variation in the solderbond in one IGBT

Figure 5: Non-destructive acoustic cross-section of a 6-die IGBT. Note the tiltedceramic members

The operational amplifier (op amp) in the world of PWM converters is

the equivalent of the CPU in the computer. The output of an op amp

is the signal used by the control IC’s comparator to define the pulse

width of the power switch.

Most, but not all, PWM control ICs have internal op amps. In most

cases, the data sheet gives a typical gain-bandwidth product as a fre-

quency at zero dB and a typical DC gain. If the designer takes these

numbers and assumes a –20dB per decade roll-off from the DC gain

level to the zero dB cross over, the typical gain profile of the op amp

can be plotted. For this discussion, we will use the UCC2842 as the

typical control IC. The UCC2842’s internal op amp and the TL431

used for the adjustable precision shunt regulator have similar gain

curves, so we will use one curve for both.

The control IC has a minimum unity gain-bandwidth product at 0 dB

of 0.7MHz and a minimum DC gain of 65dB. The designer assumes

that the gain and phase are as shown in Figure 1. These numbers

are close to the gain curve for a shunt regulator, so we will use them

in this discussion.

As long as the control loop gain requires the op amp’s gain to remain

below the limits imposed by its gain-bandwidth curve, the converter

operates correctly.

Sometimes designers try to ignore these limits, which is problematic

(see Figure 2).

P O W E R M A N A G E M E N T


Feedback Loop Op Amp Limitation Considerations

Limit wherever possible the level of noise coming into the signal chain

Pulse-width-modulated (PWM) converters have many gain elements in the feedback loop.These elements provide the means to regulate the converters output. Examples will be

examined and discussed in terms of their impact on the control loop.

By John Bottrill, Senior Applications Engineer, Texas Instruments

Figure 1: Typical gain (1a) and phase (1b) of an error amplifier

Figure 2: Gain (a) and phase (b) requirements identified


If the designer needs the limits defined in Figure 2, he can not

achieve his goal. The op amp limitations come into play and he gets

a gain and phase that is a combination of the two. The phase and

gain are as desired until the op amp limits are encountered. See Fig-

ure 3 where all three traces are shown. Not only is the gain less than

desired, but the phase-shift has significant differences than those cal-

culated.

In a situation like this the designer must revise the design to be less

than the gain of the op amps limitation over the entire loop.

Look at Figure 4 and remember to maximize the gain of each stage

within the parameters of the device used starting at the point where

the output is sensed. This affords the highest signal-to-noise ratio

(SNR) in the feedback loop.


Figure 4: Converter feedback loop

Figure 3: Gain (a) and phase (b) of op amp limits: required gain andphase; and actual gain and phase differences

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If you have a small gain at the start and a large gain at the final

stage, you have a low signal with a lot of noise at the input to the

final high-gain stage. In the final gain stage, the noise and signal are

amplified.

Conversely, if you maximize the error signal at the first stage before

noise gets into the loop, you are transmitting a large signal with a

high SNR to the final stage. This amplifies both signal and noise, but

the level of amplification needed is significantly lower and the SNR

remains high resulting is the cleanest signal possible.

To further clarify, let’s look at a typical converter where the feedback

loop is like that in Figure 4.

The designer has control over three main gain

blocks.

Stage 1 is the input resistor R1 and the feedback net-

work consisting of resistor R2, and capacitors C1 and

C2. The gain is defined as the impedance of the

series connection of R2 and C1 in parallel with C2, all

divided by R1. In this case, decreasing R1 results in

the gain curve retaining the same shape, but is high-

er.

Stage 2 consists of R3, R4, R5 and the optocoupler.

The gain here is the impedance of the parallel combi-

nation of R4 and R5 times the CTR of the optocou-

pler, all divided by R3. Increasing R4 or decreasing

R3 increases the gain.

Stage 3 consists of R6 and R5 and is simply R6 divided by R5.

Increasing R6 and decreasing R5 increases the gain.

The total gain of this network must be such that at the planned

crossover frequency the gain of this network times the gain of the

power stage (COMP to OUTPUT gain) is equal to 1 or 0 dB. On

paper, it appears there are multiple ways to achieve this. But, as in

all things, there are tradeoffs.

If you lower the gain of stage one so that you are well within the op

amps limits, A1, you can increase the gain of the control IC’s built-in

amplifier (stage 3), and everything should be good.

However, this ignores the noise sources in the converter. These

should be identified and evaluated. If they are excessive, they should

be filtered.

One of the main noise sources is the secondary bias voltage source

that provides current to the optocoupler. Any noise on this point is

translated into current through the optocoupler, and is amplified

through the remainder of the circuit.

Follow this design strategy for optimal results. First, determine the

maximum gain that can be achieved through the A1 amplifier without

violating the op amp’s parameters (see Figure 3) over the frequency

range of the error amplifier. You need to control the amplifier over the

complete frequency range so you do not run into the op amp’s limita-

tions. Next, filter the noise on the secondary bias to eliminate the

noise as much as is possible.

Having established the gain of stage one, you have to allocate the

gain stages two and three. The same applies to stage two. Achieve

the maximum gain that you can through the optocoupler that allows

you to have the voltage variations needed on the COMP pin. This

allows for the variations in load and input voltage while maintaining

regulation. These variations have to take into account the offsets in

the COMP voltage needed to cover the full range of duty cycles from

zero to maximum duty.

This range is defined in the parts data sheet. In the case of the

UC2842 (see Figure 5) there are three things to note. The two diodes

between the COMP and the current sense comparator pin (1.2V volt-

age drop), the two resistors that reduce the signal by a nominal fac-

tor of three (2.85 to 3.15) and the maximum input signal to the cur-

rent sense pin of between 0.9-1.1V.

This means that the maximum signal for the COMP pin should be

((1.1 V x 3.15) + 1.2V), or about 4.7V with a minimum of under 1.2V

(say 0.9V).

Once these are known, the design should attribute the maximum

achievable gain to the optocoupler circuit as this will give the best

SNR of this stage.

Conclusion

It is important to maximize the SNR throughout the signal chain start-

ing at the sense point in the circuit. This is done by keeping the sig-

nal and gain at stage one as high as possible. If the signal coming

out of stage one has a high level of noise, later amplification will

amplify both the signal – and the noise.

Limit wherever possible the level of noise coming into the signal

chain, for instance filter the bias voltage for the optocoupler. Remem-

ber that layout has noise. Keeping these things in mind will improve

the probability of success without having to do another layout.

References

Download datasheets and other technical documents:

www.ti.com/ucc2842-ca

www.ti.com/tl431-ca

Ask questions, share knowledge, explore ideas and help solve prob-

lems with fellow engineers at TI’s E2E™ Community power forum:

www.ti.com/powerforum-ca


Figure 5: Control IC block diagram

SIMPLY SMARTER


In those areas where a switching regulator is required, there are sev-

eral topologies based on cost, from the very basic P-ch MOSFET

paired with a Schottky diode to the use of two N-ch MOSFETS to

provide the highest efficiency possible. In those circuits, the industry

has developed a figure-of-merit (FOM) to compare one device from

another and it is defined as FOM = Qg X Rds(on). In the case of a

load switch application where switching losses do not play a signifi-

cant role, the main point of comparison has been the Rds(on) at a

certain bias voltage (Vgs), but that does not really tell you the whole

picture. We believe a better figure of merit to describe a load switch

is the Rds(on) the part can provide for a given package or footprint

area, hence FOMp = Rds(on) x Footprint. As a result, the part with

the lowest Rds(on) and the smallest footprint , will be able to provide

the best power density for a given DC load in portable devices,

where real estate and battery life are key requirements.

Power applications within handset and portable products often use

MOSFETs for a variety of uses. Some common sockets and the

types of MOSFETs used can be seen in Figure 1. The most preva-

lent socket includes a DC load switch for power management of dif-

ferent feature sets, battery charge / discharge, and general power

architecture management.

The most commonly used device for portable applications is the P-

Channel MOSFET. This preference arises from the fact that portable

architectures are battery power and the positive rail makes a solid

reference point compared to power supply operated systems where

ground is the solid reference point. Although a P-channel MOSFET,

due to carrier mobility, is a larger die for an equivalent Rds(on) speci-

fication point compared to an N-channel MOSFET, the drive circuitry

is much more simple. An N-Channel MOSFET can be either used as

a low side switch or if used as a high side switch it requires a boost

or bootstrap type topology (see figure 2). Because of this fact, the

overall circuit cost to meet performance requirements can lean

towards a P-Channel discrete FET as opposed to N-Channel gate

plus drive circuit.

When choosing an appropriate drain to source (Vds) and gate to

source (Vgs) maximum voltage tolerances, handset and portable

designers need to consider the system level maximum voltage seen.

Vgs(max) is often predicated on the voltage of single cell batteries in

these products. Many times, the MOSFETs are driven directly off of

the battery. Typical Li-Ion single cell battery voltages can vary from

2.7V to 4.2V. A solid Rds(on) performance at Vgs =2.5V with room

M O S F E T

Optimizing MOSFET Selectionin Handset and Portable DC

Load ApplicationsTrench 4 process targeting low voltage P-Channel MOSFET

There are many applications where load switches are used for sequencing, protection,power management and distribution, etc. and each of these has their own characteristics.As portable electronics such as cell phones, portable media players, personal navigationdevices, etc. continue to shrink in form factor, there is a continued need for smaller elec-tronic components to match this trend. At the same time, the expectation of componentperformance remains the same. This trend is no different for power applications using

MOSFET devices.

By Ryan Zahn, Low Voltage MOSFET Product Line Manager – Handset / Portable Productsand Isauro Amaro, Low Voltage MOSFET Applications Manager at ON Semiconductor.

Figure 1: Typical System Architecture

Figure 2: A N-channel High Side Load Switch


above 4.2V to avoid damage to the MOSFET is a good design guide-

line for selecting Vgs(max). A device with a VGS=±8V is a preferable

target to look for on this specification. Vds(max) is commonly dictat-

ed by the output voltage especially in circuits where the device is

used in a boost converter. Some handset / portable applications can

drive the MOSFET with internal rails operating off of the battery (3.3V

or 1.2V) and drive the various load as well from a tightly control inter-

nal rail. This could allow for safe operation of the MOSFETs with a

Vgs(max) as low as ±5V and Vds(max) as low as -8V.

With a P-Channel, -20V Vds(max) and ±8V Vgs(max) MOSFET as a

very common product selection for handset and portable DC load

applications, the next most common design guidelines involve the

tradeoff between (FOMp) Rds(on) performance vs. footprint area.

The Rds(on) targets for the designer will be largely based on the cur-

rent of the loads and the efficiency performance targeted. Very com-

mon Rds(on) targets are <50mOhm for front end power management

switches. These switches often power off the entire backside archi-

tecture of a handset / portable device when in standby mode.

Because this power rail supplies several loads, the current typically is

high. Requiring lower Rds(on )and high current carrying capability

sometimes in the 2-8A peak for distributed systems. In the same

manner, charge of the battery typically requires higher current carry-

ing capability and efficiency for example in Lithium-Ion batteries you

can have 1A continuous for up to 1 hour (See Figure 3).

Also using USB ports to power up accessories you have to be able to

handle 5V and supply a load current anywhere from 100mA to

500mA continuously. For the individual loads, the MOSFET can be

sized depending on three main factors, the current requirements, the

output voltage, and the type of load. The ON resistance and the cur-

rent determine the drop out voltage, so you must keep in mind the

maximum drop out voltage that your system can tolerate. Some

applications could often require a 100mOhm to roughly 300mOhm

while very low current loads could operate effectively with as high as

1 to 5 Ohms. The type of load also will help in defining the in-rush

current capability of the MOSFET. Capacitive loads in particular can

give high current surges that can be controlled by slowly switching

them ON. In order to do so it is common to use a large P-ch MOS-

FET to handle the load and a small signal N-ch MOSFET to control

the turn on speed using a resistor to control the slew rate (R2). This

is also often the case when the drive signals are different from the

supply voltage.

Figure 4 shows the trend of P-Channel -20V Vds / +-8V Vgs MOS-

FETs from several vendors in very small packaging that is commonly

seen in handset / portable market spaces. Rough groupings of the

release dates of these products are shown. As seen in the figure,

there is a general trend of lower Rds(on) and smaller package foot-

print to maintain the trend of improved power density in handset /

portable market spaces for DC applications.

ON Semiconductor, in order to maintain an industry leading position

in power density figure of merit, has recently released products on a

Trench 4 process targeting low voltage P-Channel MOSFET applica-

tions with -20V Vds(max) and ±8V Vgs(max). This represents a

40%+ shrink in Rdson from previous ON Semiconductor P-Channel

technologies.

www.onsemi.com

Figure 3 - Typical Lithium-Ion Charge profile (CC-CV)

Figure 4: Rdson (mOhms) vs. Footprint (mm^2) of Key ProductReleases of P-Ch -20V Vds / ±8 or 12V Vgs MOSFETs

Texas Instruments introduced a highly inte-

grated protection device that integrates hot-

swap control and precise digital current mon-

itoring. The TPS2480 controller provides the

most accurate measurement of power

usage, within one percent accuracy over

temperature, allowing system designers to

generate a detailed history of system per-

formance, anticipate failures and implement

advanced system power health monitoring.

The TPS2480 is designed to minimize in-

rush current and protect the load and the

FET from over-current or short circuit events.

It controls an external N-channel MOSFET

switch and provides accurate voltage, cur-

rent and power monitoring via an I2C inter-

face. This information enables telecommuni-

cations equipment, enterprise networking

products, automation control systems and

medical equipment to communicate precise

information on their operating status, take

action to respond to critical situations, and

extend usable lifetime of deployed equip-

ment.

TI also introduced the new TPS2492 high-

voltage, power-limiting hot-swap controller to

support designers who desire increased pro-

tection against voltage surges using an ana-

log output signal for current monitoring. The

controller provides excellent transient immu-

nity, rated up to 80 volts, and filters out nui-

sance faults with a settable timer. A program-

mable overvoltage protection threshold also

protects loads from unsafe voltage levels.

www.ti.com

42

N E W P R O D U C T S


Hot-Swap Controllers Integrate Digital Current Monitoring

International Rectifier has announced the

expansion of its family of automotive Direct-

FET®2 power MOSFETs that deliver excep-

tional power density, dual-sided cooling and

minimal parasitic inductance and resistance

for heavy load applications, including Electric

Power Steering, power supplies, battery

switches on hybrid electric vehicles and Inte-

grated Starter Alternators on micro hybrid

vehicles.

The automotive-qualified DirectFET®2

devices offer overall system level size and

cost reductions along with superior perform-

ance and efficiency when compared to tradi-

tional standard plastic packaged compo-

nents. Featuring a PCB footprint 60 percent

smaller than a D2Pak, the AUIRF7738L2

and AUIRF7737L2 DirectFET®2 devices

deliver exceptionally low on-state resistance

(RDS(on)), while the AUIRF7736M2 features

a PCB footprint the same size as a 5x6 mm

PQFN or SO-8 package with low RDS(on) of

2.5mOhm, making it suitable for more cost

sensitive, lower power applications.

Utilizing IR’s advanced Trench silicon

process, this expanded DirectFET®2 portfo-

lio offers automotive systems designers the

proven benefits of exceptional power density,

dual-sided cooling and low parasitic package

inductance and resistance in a robust, reli-

able and scalable power package.

The AUIRF7737L2 and AUIRF7738L2 share

a common Large Can PCB footprint with the

previously released AUIRF7739L2 making

the devices highly desirable components

where a scalable system design is required.

With a package current rating of 315 A for

both devices, the DirectFET® package

places no constraint on current capability of

the silicon. Moreover, the maximum package

current ratings far exceed the limits of tradi-

tional DPak and D2Pak packages.

The devices are qualified according to AEC-

Q101 standards, feature an environmentally

friendly, lead-free and RoHS compliant bill of

materials, and are part of IR’s automotive

quality initiative targeting zero defects.

www.irf.com

Family of Robust, Reliable Automotive DirectFET2

Linear Technology announces the LTC3105,

a high performance, synchronous boost con-

verter that incorporates maximum power

point control (MPPC) and starts up with

inputs as low as 250mV. The LTC3105 oper-

ates over an extremely wide input range of

0.2V to 5V, making it ideal for harvesting

energy from high impedance alternative

power sources, including photovoltaic cells,

thermoelectric generators (TEGs) and fuel

cells. The LTC3105’s internal 400mA syn-

chronous switches maximize efficiency while

its Burst Mode® operation offers quiescent

current of only 22uA, further optimizing con-

verter efficiency over all operating condi-

tions. A user-programmable MPPC set point

maximizes the energy that can be extracted

from any power source without collapsing its

internal voltage.

The LTC3105 is ideally suited to power wire-

less sensors and data acquisition applica-

tions. Surplus or ambient energy can be har-

vested and then used to generate system

power in lieu of traditional wired or battery

power, which may be expensive or impracti-

cal. Typically, these applications require very

low average power, but require periodic puls-

es of higher load current. For example, the

LTC3105 can be used in wireless sensor

applications where the power load is

extremely low when the sensor is in standby

mode, interupted by periodic high load

bursts, when the circuitry is powered up to

take measurements and transmit data.

www.linear.com/3105

Step-Up DC/DC Converter

43


SemiSouth Laboratories announced a wide

range of SiC power Schottky diodes includ-

ing the 30A rated SDP30S120 - industry’s

highest current 1200V part to be commer-

cially available in a TO-247 package.

The full 1200V, ROHS-compliant product

range spans 5-30A with lower current (5 and

10A) diodes packaged as T0-220 parts while

10, 20 and the industry-leading 30A devices

are offered in the TO-247 package. All

diodes in the family are designed with an

advanced integrated junction barrier technol-

ogy to simultaneously enable low forward

voltage with low leakage currents and high

power density for compact power designs.

Other features include negligible reverse

recovery and high reliability.

While the lower current parts are drop-in,

risk-free high performance alternatives for

other manufacturers’ parts, the SDP30S120

demonstrates SemiSouth’s technology lead-

ership in silicon carbide technology with its

outstanding 30A current capability. Com-

ments Dan Schwob, Vice President Sales

and Marketing: “These parts can benefit

many applications including solar energy

where they can be used in the boost sector

of solar inverters to dramatically improve effi-

ciency. Other uses include SMPS, PFC

devices, induction heating, UPS and motor

drives.” He concludes: “We expect to

expand our silicon carbide diode Schottky

power diode family to include 60A parts in

the very near future. This will put us way out

in front of our competition and be particularly

exciting for manufacturers of 30kW solar

inverter systems.”

www.semisouth.com

Wide Range of SiC Power Schottky Diodes

LEM introduces the DI series/Shunt isolator

to enable high-accuracy current measure-

ments in rail traction applications. DI Series

transducers measure to a high degree of

precision the very small voltages developed

across low-resistance ohmic shunts in the

primary power conductors feeding rail trac-

tion motors, spanning ranges of 30 to 200

mVRMS.

Featuring LEM’s patented insulating technol-

ogy, the DI series has specifically been

designed to enable rail-traction designers to

meet the provisional EN 50463 standard for

on-board energy monitoring. When used

with a shunt Class 0.2 accuracy, the DI

reaches the required Class 1R accuracy.

The DI can then be part of the measurement

chain of any on-board energy meter, as a

key element in the recording of energy con-

sumed (or returned to the supply under

regenerative braking), according to the stan-

dards set out in the provisional standard.

Coupled to a shunt used for current meas-

urement, the DI provides necessary voltage

insulation (withstanding 18.5 kVRMS/ 50

Hz,/ for 1 minute as insulation test voltage)

that is essential due to the high-voltages met

in vehicles that are supplied with energy

from networks up to 3000 V.

DIs can easily be added to any existing

shunts already mounted into the application

when insulated operation is necessary.

With a low current consumption of 20-25 mA

(+ the output current), a wide frequency

bandwidth of 10 kHz, LEM’s DI shunt isolator

meets the demands of modern rail systems

and fulfils all new EMC requirements. Other

key features include a high level of partial

discharge extinction voltage, adherence to

safety standards, high quality and long life,

together with low weight and flexible

mechanical and electrical output to adapt to

customer needs.

www.lem.com

Shunt Isolator to Meet prEN 50463 for Traction

Tyco Electronics announced that it has qualified its family of Poly-

Switch nanoASMD, microASMD, miniASMD, ASMD and AHS sur-

face-mount devices (SMDs) to help vehicle manufacturers meet

industry safety and reliability standards, reduce system cost and

improve the efficiency and reliability of electronics designs. The auto-

motive-grade PolySwitch devices have been tested to follow the

guidelines of the automotive industry’s AEC-Q200 standard for elec-

tronic components.

Available in footprints as small as 1206, the devices provide current

ratings from 0.05 to 3.0A and voltage ratings from 16 to 60VDC. They

help provide overcurrent and overtemperature protection for electron-

ic control units (ECUs), I/O ports and traces, telematics and infotain-

ment systems, and motor and motor control circuits. Most devices

are rated from -40°C to +85°C, but for higher temperature, under-

hood applications the PolySwitch AHS device family is rated up to

125°C.

Automotive-grade PolySwitch devices are capable of passing seven-

teen electrical and environmental stress tests that require electrical

performance verification prior to and after each stress. The electrical

verification tests are intended to ensure that parts meet performance

specifications for resistance, time-to-trip (TtT) and hold current at

three temperatures (-40°C, 25°C and max T).

The AEC-Q200-qualified automotive-grade SMD circuit protection

devices are characterised by specific additional values determined

after stringent testing, and have been assigned specific automotive

part numbers to reflect their qualifications. The full family of automo-

tive-qualified PolySwitch SMD devices includes more than thirty prod-

ucts in various voltage ranges. They are Pb- and halogen-free, RoHS

compliant and are compatible with high-volume SMD assembly

processes.

www.tycoelectronics.com

www.circuitprotection.com

PolySwitch Devices Qualified to AEC-Q200



Sharp is expanding its portfolio of energy-

harvesting components with new monocrys-

talline solar panels for portable applications.

Compared to their predecessors, the new

solar panels of the models LR0GC11 and

LR0GC13 achieve a one-third better efficien-

cy and a conversion rate of 16.5%. On a

surface of just under 27 cm² the LR0GC11

achieves a maximum output performance of

390 mW; its smaller sister, the LR0GC13,

supplies a maximum of 180 mW with just

half of the surface area.

Sharp achieved this significant increase in

conversion efficiency by redesigning the

solar panels. With the new monocrystalline

cells, all stripe conductors are placed inside

of the module so that no active surface is

shaded any longer. Nothing changes with

the double wiring of the cells. It guarantees

that, even in the case of a fracture of the

cells, the full power output of the panel

remains intact. This plays an important role

for all mobile applications which can be

exposed to high mechanical stress occasion-

ally caused e.g. by being dropped.

The design is also a major leap forward with

respect to aesthetics, because the new gen-

eration of small solar panels distinguishes

itself by virtue of a completely homogeneous

surface which is not interrupted by stripe

conductors. In addition, with the new photo-

voltaic elements, design engineers have

much more leeway in the colour configura-

tion of applications. Alongside classic

anthracite, Sharp solar panels can be

designed, on request, in any conceivable

colour if appropriate quantities are ordered.

Depending on the colour this additional layer

does indeed slightly decrease the output

performance of the panel but, even with

highly absorbent colours such as red, the

conversion rate still lies way ahead of that of

previous models. In addition, the new panels

are appreciably thinner and lighter than the

previous models. The thickness is only 0.65

millimetres for both models (LR0GC11 and

LR0GC13).

[email protected]

Highly Efficient Monocrystalline Solar Components

CUI Inc’s power line, V-Infinity, announced

the release of two digital non-isolated DC-

DC Point of Load (POL) modules. The new

Novum series has been developed for

designers to realize better energy efficien-

cies and improved time to market compared

to the traditional analog approach. Offered in

12 A and 25 A configurations, the NDM1-12-

12 and NDM1-25-12 models are digital

devices that have full monitoring, program-

ming, and configuring capabilities. These

uniquely digital attributes provide superior

functionality and support current monitoring,

temperature sensing, voltage margining, and

voltage sequencing.

The Novum series utilizes Powervation’s

patented Auto-control™ technology which

will allow the new modules to ensure stability

and improve transient responsiveness. Both

modules operate off a wide input voltage

range of 8.5 V to 14 V and can be pro-

grammed to support output voltages

between 0.6 V and 2.5 V. Programming is

handled through a SMBus serial interface

and the Novum modules utilize industry

standard PMBus commands for communi-

cating with other devices.

The NDM1-12-12 efficiency is up to 95% in a

compact DIP package measuring 0.5” x

0.925” x 0.46“. Power fault management

includes over temperature, over current, and

over voltage protections. The NDM1-12-12

is available through Digi-Key and start at

$17.91 per unit at 500 pieces. Contact CUI

directly for OEM pricing. Demonstration kits

are also available through Digi-Key for $149.

The kits will include 12 A and 25 A module

demonstration boards and provide access to

the V-Infinity user friendly GUI.

www.cui.com

Digital DC-DC POL Module Series

International Rectifier has introduced a fami-

ly of SupIRBuck™ integrated point-of-load

(POL) voltage regulators in a compact 4 x 5

mm package. The devices, tailored for ener-

gy-efficient server, storage, telecom, netcom

and set-top box applications offer the same

efficiency and functionality as previous gen-

eration devices in a 33 percent smaller foot-

print.

The IR38(53)(56)(59) SupIRBuck voltage reg-

ulators integrate a high performance con-

troller with latest generation MOSFETs in a

slim 4 x 5 mm PQFN package, and deliver 4

A, 6 A and 9 A output current respectively to

achieve more than 96 percent peak efficiency.

New features include over-voltage protection,

an external synchronization option to reduce

noise and EMI in multi-rail systems, true out-

put voltage sensing option for adjustable

PGOOD, and OV threshold setting.

The devices eliminate the need for traditional

dual stage POL conversion and save energy,

size and cost by operating directly from 12

Vin. While optimized for 12 V input voltage,

superior efficiencies are also achieved in

applications with single 5 V input voltages.

As a result of programmable switching fre-

quencies up to 1.5 MHz and small 4 x 5mm

footprint, the new voltage regulators shrink

size and cost, in addition to achieving higher

power density. Moreover, the common foot-

print of the devices provides design flexibility

and allows cut-and-paste layout for fast time-

to-market.

SupIRBuck family features also include pro-

grammable hiccup current limit, programma-

ble soft start, enhanced pre-bias start up,

thermal protection, enable pin with voltage

monitoring capability, Power Good output for

under-voltage and over-voltage detection, +/-

1 percent accurate 0.7V reference in 0-

125°C temperature range, and -40oC to

125oC operating junction temperature.

www.irf.com

Point-Of-Load Voltage Regulators with 33% Smaller Footprint


CUI Inc’s power

line, V-Infinity,

announced the

release of a

new line of

rugged DC-DC

converters that

provide 400 W of output power. The

VFK400 series is a chassis mount solution

measuring 7.8” x 5.0” x 1.5” and includes an

integrated heat sink for improved thermal

performance. The aluminum heat sink

allows the unit to operate at higher tempera-

tures with a minimal amount of air flow.

The VFK400 series accepts an ultra-wide

4:1 input and can support either 10-36 Vdc

or 18-75 Vdc isolated input voltages. The

wide input range is very useful when being

driven from a fluctuating device like a battery

which can see both charging and discharging

conditions. The DC-DC converter is offered

in three different regulated output voltage

versions: 12, 24, and 48 Vdc. High efficien-

cy, fast response, tight regulations, remote

sense and remote On/Off control make these

converters very useful in many industrial and

communications applications.

Standard features include over-temperature,

over-current, and input transient voltage pro-

tection. With an external input fuse, the con-

verter can also protect against accidental

polarity reversal. The VFK400 series is avail-

able through Digi-Key at $388.94 for 500 pcs.

Contact CUI directly for OEM pricing.

www.cui.com

400 W DC-DC Converter with Integrated Heat Sink

Maxim Integrated Products introduces the

MAX4936/MAX4937 fully integrated octal

high-voltage transmit/receive (T/R) switches.

These switches integrate clamping diodes to

isolate the low-voltage receive path from the

high-voltage transmit path, thus protecting

the receiver input from voltage spikes due to

leakage currents flowing through the T/R

switches. Maxim's integrated solution uses >

50% less board space than discrete circuits

while providing high bandwidth, low jitter,

and low signal distortion. The

MAX4936/MAX4937 are ideal for use in

ultrasound imaging and industrial flaw-detec-

tion probes, in which board space is at a

premium.

The MAX4936/MAX4937 feature eight indi-

vidually programmable switches controlled

through an SPI(TM) interface with a 12-bit

shift register and transparent latch. These

features simplify device operation when

updating the states of the T/R switch; they

ensure that all switches are off at power-on;

and they reduce noise due to clock

feedthrough.

www.maxim-ic.com

Transmit/Receive Switches Integrate Clamping Diodes

Intersil Corporation as part of its new

HEV/EV system solution, introduced a sec-

ond device that provides a 12-channel auto-

motive grade Li-Ion battery fault and safety

monitor.

To address the safety requirements of an

HEV/PHEV(plug-in hybrid)/EV Li-Ion battery

system, the ISL78601 provides independent

and redundant fault monitoring when used in

conjunction with the ISL78600 battery man-

agement system (also introduced today, see

related news release).

To achieve the highest possible reliability for

intra-system communication, the ISL78601

utilizes a high noise immunity and transient

tolerant communication scheme. This fully

differential daisy-chain architecture allows

the use of low cost twisted pair wiring to

stack multiple battery packs together while

protecting against hot plugging and high volt-

age transients. The benefits offered by the

Intersil HEV/EV system solution can signifi-

cantly reduce overall battery management

system costs.

As part of the system's safety features, the

ISL78601 has extensive built-in fault detec-

tion for its internal functions and detects

external faults such as over and under volt-

age. The device also includes a watchdog

timer to detect communication failures.

www.intersil.com

Multi-Cell Li-ion Battery Monitor for Electric Vehicles

WHEN WE IMPROVE OUR PHOTOCOUPLERSWE THINK BIG – AND SMALL.As a leading manufacturer of photocouplers, Toshiba’s product range continues to pioneerinnovation. Like lower power consumption and higher switching speed. Yet it’s all in newsmaller packages. Our latest SDIP package is 50% smaller than previous devices andis ideal for circuits that require the reinforced isolation demanded for international safetycertification.

Whether your application is for industrial or domestic appliances, drives or factoryautomation interfaces, when you want less, Toshiba gives you more.

Visit us today at www.toshiba-components.com/photocouplers



Isabellenhütte is launching the VLx resistor

series, resistors with unmatched perform-

ance. Reversing the length to width ratio

resulted in expanding the resistance range

to extremely low values (i. e. 1mOhm in size

0612) and enabled other remarkable

improvements. The larger soldering and con-

tact pads are increasing the mechanical sta-

bility of the solder joints during temperature

and power cycling and guaranty at the same

time a much better heat flow into the PC

board. A new mechanical construction signif-

icantly increases the mechanical stability

and the internal heat resistance (Rthi as low

as 15K/W) with the consequence that the

heat produced within the components is con-

ducted very efficiently to the terminations

and out of the resistors. Despite their small

size, the power rating of the resistors is very

high in comparison to similar components.

The operation temperature range is between

-65°C and +170°C. The above described

unique properties guarantee the application

under full power even at high temperature (i.

e. size 1020: 2W permanent power at

140°C, maximum current 45A). With

50ppm/K the TC value is extremely low con-

sidering the low resistance values.

Sample quantities are available from Febru-

ary 2011 with resistance values of 1, 3, 10

and 50mOhm with tolerances of 1 and 5%.

Serial production of the resistors will most

probably start by mid-2011.

Some possible applications for VLx resistors

are control systems for the automotive

industry, power modules, frequency invert-

ers, switch mode power supplies as well as

current sensors for semiconductor power

hybrids.

www.isabellenhuette.de

Product Range Featuring Long Side Termination for High Performance

Cornell Dubilier’s catalog pres-

ents CDE’s high-performance

capacitors for power electron-

ics with special emphasis on

CDE’s power film capacitors

and high-voltage screw termi-

nal and snap-in aluminum

electrolytic capacitors. Within

the 244, full-color glossy cata-

log pages are the special

capacitors needed for power-

electronics applications such

as wind and solar energy, UPS

systems, motor drives, welders

and power supplies.

The back cover includes a helpful “At a Glance” guide, which fea-

tures leading edge aluminum electrolytic and film dielectric capacitors

designed to solve the unique demands presented within each of the

electronic stages of power inverters.

“This new catalog is geared for the Power Electronics Designer and

includes full application guides for each section,” says Scott Franco,

Director of Market Development for Cornell Dubilier Electronics. “It is

divided into 4 major capacitor segments: Aluminum Electrolytics, AC

Films, DC Films and Mica, with the types, voltages and sizes used

most in Power Electronics designs.”

The new catalog is available now from Cornell Dubilier.

www.cde.com

Catalog Features Capacitors for Power Electronics

Texas Instruments Incorporated introduced

two new power management integrated cir-

cuits for point-of-load designs that raise the

bar for size, power density and performance.

TI’s TPS82671 and TPS84620 integrated

power solutions ease design and speed

time-to-market in portable electronics, com-

munications and industrial applications.

The TPS82671 is the industry’s smallest

integrated plug-in power solution at 6.7

mm2, providing 90 milliamps per square mil-

limeter. The device combines all external

components in TI’s new MicroSiP™ package

with a 1-mm height -- easing design for 600-

mA portable electronics, such as smart-

phones. The TPS82671 operates at a very

low 17-uA quiescent current and achieves

power efficiency of greater than 90 percent

from an input voltage of 2.3 V to 4.8 V. A

unique PWM frequency dithering feature

reduces noise and improves performance in

radio frequency-sensitive designs.

www.ti.com/tps82761-preu

TI’s new 6-A, 14.5-V TPS84620 achieves a

power density of greater than 800 watts per

cubic inch with up to 95 percent efficiency

and 30 percent better thermal dissipation

than competitors. The integrated step-down

solution combines the inductor and passives

onto one device, and requires only three

external components, resulting in a complete

solution in a space less than 200 mm2. The

TPS84620 supports a variety of high-power

telecom infrastructure and industrial systems

that use DSPs and FPGAs.

www.ti.com/tps84620-preu

www.ti.com

Breakthrough in High-Density Power Solutions for POL Design

www.bodospower.com December 2010

Mitsubishi Electric is introducing its 19.2”

color TFT-LCD module for 16:3 ratio images

(1920 x 360 pixels) offering a broad range of

wide-format display

and design solu-

tions. The product

AA192AA01 will be

equipped with a

built-in LED driver

and white Light Emit-

ting Diodes (LED)

backlights, providing

a longer lifetime and

excellent perform-

ance as well as an

inverter-less design,

and will be available

through Mitsubishi

Electric sales sites.

Mitsubishi Electric

has created a highly durable module meas-

uring 496.5mm x 109.2mm for the display of

16:3 ratio images.

The module contains a built-in LED driver to

achieve a more compact system design and

a better cost effectiveness at customer’s

applications. At 25°C, LED backlights have

an operating lifetime of at least 60,000 hours

making it suitable for long-term use applica-

tions. The TFT-LCD module has a typical

brightness of 500cd/m2.

The AA192AA01 achieves a top level wide

operating temperature range from -30°C to

80°C, making it useful in severe climatic

environments. It also features Mitsubishi

Electric’s proprietary color conversion tech-

nologies (Natural Color Matrix) for adjusting

or replacing colors lost due to LCD charac-

teristics, resulting in clear, vivid colors and

images.

www.mitsubishichips.eu

19.2” Color TFT-LCD Module with 16:3

Wide-Format

Electronic Concepts is a manufacturer of

Film Capacitors with its European Headquar-

ters located in Galway, Ireland. They have

just launched a new series of DC “Link” High

Current Film Capacitors specifically targeting

the ever expanding Electric and Hybrid Elec-

tric Vehicle Market. The key characteristics

of the product range include:

• The capacitance values range from 500ìF

to 1,000ìF

• The voltage range for the product line is

450VDC to 1,000VDC

• The capacitors have been designed to be

capable of operating up to 200 A (RMS)

• The maximum hotspot temperature is

110°C

• The maximum non-operating temperature

for the capacitors is 125°C

• The self inductance of the capacitors is as

low as 10nH

• The life expectance for the product line

has been calculated to be > 15,000 hours

The range of Capacitors has been designed

to be compatible with the most commonly

used IGBT-Modules in production today. The

compact designs allow for maximum volu-

metric efficiency and ease of mounting to the

IGBT-Module.

In addition to the standard product range,

Electronic Concepts still offer customised

solutions on specific request. Electronic

Concepts Design Engineers endeavour to

provide solutions and technical support to all

current and potential customers.

www.electronicconcepts.ie

DC “Link” Capacitors for Electric

Drive-Train Inverters

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Future precision.Future performance.Now available.



APEC 37

Bicron 33

CT Concept Technologie C3

CUI 23+31

Danfoss Silicon Power 11

Darnell 17

EMV 2011 19+21

Fuji 9

GvA C2

Infineon 5

International Rectifier C4

Intersil 39

ITPR 15

KCC 7

Lem 47

LS Industries I1

Payton 15

PCIM 13

Syfer 41

Toshiba 45

Tyco 27

Würth Electronic 25

ADVERTISING INDEX

Silicon Laboratories Inc. introduced a family of isolated gate drivers

designed for high-power Class D audio systems with output power

ranging from 30 Watts to 1,000 Watts. The new Si824x Class D

audio driver family provides exceptional high-fidelity performance,

robust noise tolerance and precise dead-time control for a wide

range of digital audio applications such as home entertainment sys-

tems, powered speakers, guitar amplifiers, public address and out-

door speaker systems, alarms and sirens, and car stereos.

Class D amplifiers - the solution of choice for low-power audio

designs - are rapidly replacing Class AB amplifiers in high-power

audio applications. As the high-fidelity market increasingly adopts dig-

ital audio technology and high-efficiency standards, developers are

designing energy-efficient "green" systems that meet Energy Star

guidelines while delivering exceptional audio performance and

enabling BOM cost reductions. Silicon Labs' Si824x audio drivers

provide an ideal solution for these emerging high-power Class D

audio designs.

www.silabs.com/pr/audio-driver

Isolated Gate Drivers Provide Superior Audio Performance

for Class D Applications

Toshiba Electronics Europe has expanded its photocoupler portfolio

with two AC input logic-IC couplers capable of data transmission

rates up to 5Mbps. The TLP2095 and TLP2098 suit programmable

logic controllers, communications equipment, digital interface circuits

and other applications where a combination of high-speed data trans-

mission, electrical isolation and low power operation is required.

Designed to support supply voltages from 3.0V to 20V, the TLP2095

and TLP2098 provide buffer logic and inverter logic totem pole out-

puts respectively. Maximum switching time is just 250ns, and per-

formance is guaranteed at temperatures between -40ºC and 100ºC.

The minimum isolation rating for each device is 3750Vrms and inter-

nal Faraday shields provide common mode transient immunities of

±15kV/μs.

Both of the photocouplers are supplied in a compact MFSOP pack-

age measuring just 4.4mm x 3.6mm x 2.5mm. This package inte-

grates two GaAlAs infrared LEDs that are optically coupled to a high-

gain, high-speed photodetector. A maximum input threshold current

of ±3mA and a maximum operating current of 3mA make the cou-

plers ideal for applications where power budgets need to be kept to a

minimum.

www.toshiba-components.com

High-Speed, Low-Power Photocouplers

2SP0115T Gate DriverUnleash the full power of your converter design using the new 2SP0115T Plug-and-Play driver. With its direct paralleling capability, the scalability of your design into highest power ratings is unlimited. Rugged SCALE-2 technology enables the complete

the size of 17mm dual modules. Combined with the CONCEPT advanced active clam-ping function, the electrical performance of the IGBT can be fully exploited while keeping the SOA of the IGBT. Needless to say that the high integration level provides the best possible reliability by a minimzed number of components.

FeaturesPlug-and-Play solution1W output power15A gate current<100ns delay time± 4ns jitterAdvanced active clampingDirect- and halfbridge modeDirect paralleling capability2-level and multilevel topologiesDIC-20 electrical interfaceSafe isolation to EN50178 UL compliant50.- USD @ 1000 pieces

www.IGBT-Driver.com

SAMPLES AVAILABLE!

CT-Concept Technologie AG, Renferstrasse 15, CH-2504 Biel, Switzerland, Phone +41-32-344 47 47

UnleashSheer Power!

Features

• Low thermal resistance to PCB (down to <0.5°C/W)

• High Current Package – up to 100A continuous

• 100% RG tested

• Low profi le (<0.9 mm)

• Industry-standard pinout

• Compatible with existing surface mount techniques

• RoHS compliant containing no lead, nobromide and no halogen

• MSL1, industrial qualifi cation

The IR Advantage

• Increased power density

• Increased reliability

• Multi-vendor compatibility

• Easier manufacturing

• Environmentally friendlier

Standard Gate Drive

Logic Level Gate Drive

For more information call +49 (0) 6102 884 311 or visit us at www.irf.com

Offering Optimized Performance and Cost for a Given Application

Part Number Package Voltage CurrentRDS(on)

Max. @10VQG Typ@10V

IRFH5004TRPBF PQFN 5x6mm 40 V 100A 2.6 mΩ 73 nC










IRFH5015TRPBF PQFN 5x6mm 150 V 56A 31 mΩ 33 nC



Part Number Package Voltage CurrentRDS(on)

Max. @4.5VQG [email protected]

IRLH5034TRPBF PQFN 5x6mm 40 V 100A 2.4 mΩ 43 nC



Introducing 40 V – 250 VMOSFETs in High Current Package

THE POWER MANAGEMENT LEADER

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