non-dimmable lower power led solutions

1

Non-Dimmable Lower Power LED Solutions

2 • Steve West • Nov-12 Confidential Proprietary2

Low Power LED Driver SpaceDecorativeand Globe

General ServiceA19/A21

E26/7 Base

Small Constant Current Drivers

Typically < 15 W

Directional/Spot Lamps

GU10/PAR/BAR

Wide variety of power levels, form factors, many need isolation

Small Fixtures

Desk LampsUnder-cabinet

Accent

E14

B22


Isolated Considerations

• For bulbs, protection from electrical shock protection can be done by electrical or mechanical means

• Electrical isolation simplifies the mechanical design and eases safety agency approval and allows the use of off the shelf heat sinks and housings

• Transformer provides isolation• Safe Extra Low Voltage Level is < 60 Vdc (UL1993, EN 60598-1 etc)• < 18 LEDs in series (Vf ~ 3.3V) is the practical upper limit

• Opto-coupler feedback or primary side control (PSC) compensates for any variation to line or load


Primary Side Control Block Diagram

CCCVControl

FlybackController

Advantages• Reduces Parts Count• Simplifies PCB Layout • Saves Space• Increases Efficiency• Simplifies Safety Analysis

CCCV Loop Components

• Dual Op Amp• TL431 or Zener Reference• Bias for Opto-coupler• Bias Regulator for Op Amp• Current Sense Resistor• Voltage Sense for OVP


Challenges of Primary Side Control• Control algorithm must deal with many variables

• LED string voltage and input line voltage variation• Component variation (transformers, FET, IC, resistors)

• Target is to precisely regulate current over Wide Vf support• LED forward voltage changes with temperature and lot-to-lot

• No need to bin LEDs to get tight Vf

• One driver design can be used for a range of products (optics/LED etc) simplifying design and reducing engineering cost

• Future proof designs so as LEDs improve, same driver can be used

• NCL3008x PSC family was designed to achieve best-in-class performance using Quasi-Resonant Approach


Flyback Output Current

• t1 is the reset time of the leakage inductor.

• tdemag is the primary inductor reset time.

• IL,pk is the controlled magnitude in a current mode circuit: IL,pk = VCS / Rsense

• The controller measures t1, tdemag and control IL,pk to maintain Iout constant:

time

t1 t2tdemagton

IL,pk

NspID,pkIpri(t)

Isec(t)

1 2sw

refout sec demag sw L,pkT

sp sense

VI I ( t ) f t ,t ,T ,I

N R


NCL30080 Block Diagram

• Quasi-Resonant Control for High Efficiency and low EMI

• PSR control

• Robust Protection• Short Circuit• Overvoltage• Shorted Winding• Vcc UVLO• Shorted CS pin


NCL30080 Primary Side Controller

Line voltagesensing

Line feed-forward adjustment

Inductor currentsensing

Leakageinductancereset timesensing


NCL30080 is one of a FamilyName Pins Thermal

Foldback Analog/Digital

DimmingAdjustable

OVP Application 5 Step LOG

Dimming

NCL30080A/B 6 No No No Retrofit/Ballast NoNCL30081A/B 6 No No No Dimmable Bulb YesNCL30082A/B 8 Yes Yes Yes Bulb/Ballast/

Smart Lighting/Higher Power

No

NCL30083A/B 8 Yes Soft-start Yes Dimmable/ Higher Power

Yes

• A: Latched faults (Output SCP, OTP, Winding/output diode SCP)• B: All faults auto-recoverable

• Packages:

SOIC8 AvailableIn Q3


Review of NCL3008x Features• Wide Vcc and low startup current simplify

biasing and achieving fast startup

• Wide Vcc range allows one design to support range of LEDs without the need of a regulator on Aux winding

• Strong drive capability with gate drive clamp

• Wide temperature range along with built in auto-recoverable thermal shutdown

• Hysteretic OVP plus programmable over voltage protection on 8 pin version

• Robust protection and dimming options

Typical Parmeters Value Units

Vcc(on) 18 VdcVcc(off) 8.8 Vdc

Startup Current 13 µAVcc-OVP 28 Vdc

Maximum Vcc 35 Vdc

Gate Drive Clamp Voltage 12 VdcSink Current 500 mA

Source Current 300 mA

Minimum Operating Temperature -40 °CMaximum Operating Temperature 125 °C

IC Thermal Shutdown (TSD) 150 °CTSD Hysteresis 50 °C


Vcc-min (Max) = 9.4 V

OVP (Min) = 26 VPower limit for

transformer size / design

Aux

Win

ding

Bia

sing

sets

a li

mit

for

IC o

pera

tion

LED Current (mA)

LE

D F

orw

ard

Vo

ltag

e

480 700

22 V

9.5 V7.6 V

14 VSingle transformer

can cover wide LED current& Vf range with minor

BOM change (current setting resistor)

Wide Vf Flexibility Means Designer Can use One Transformer Design for Many Models


Typical NCL3008x Current Regulation Variation

• Iout = 480 mA (nom)

• 3 LED = 9.5 V• 7 LED = 21.9 V

• Same Transformer and MOSFET

• Min-max Iout variation was 12 mA

• Min:– Vin =240 Vac– Vf = 21.9 Vdc– Iout = 476 mA

• Max:– Vin =120 Vac– Vf = 9.52 Vdc– Iout = 488 mA

Line Voltage (Vac)


NCL30082 Efficiency from 4.6 – 10 W Pout

• Iout = 480 mA (nom)

• 3 LED = 9.5 V• 7 LED = 21.9 V

• Same Transformer and MOSFET

• Min-max Iout variation was 12 mA

• Min:– Vin =240 Vac– Vf = 21.9 Vdc– Iout = 476 mA

• Max:– Vin =120 Vac– Vf = 9.52 Vdc– Iout = 488 mA


Flyback Controllers Support Buck-Boost

LED String

NCL30000Controller

EMIFilter

MainsInput

+

Input Sense

LED Sense

Terminator

Current Sensor

Scaling

Classic FlybackController

With a classic Flyback controller, still need level shifter to sense LED current


NCL3008x Control Supports Buck-Boost

LED String

NCL30000Controller

EMIFilter

MainsInput

+

Input Sense

LED Sense

Terminator

Current Sensor

Scaling

NCL3008xSeries

Non-isolated buck boost with PSC also eliminates components like snubberand improves efficiency


Reference Design Boards• NCL30081LEDGEVB (Small Board)

• NCL30080/1 Isolated Flyback • Intended for GU10 form factor• 3-4 LEDs at 500 mA• 100-265 Vac, 83% typ efficiency

• NCL30083FLYGEVB – 10W• NCL30082/3 Isolated Flyback• Intended for A19/PAR/Drivers• 3-7 LEDs at 500 mA (9.5-22V)• Resistor change for 700 mA (7-14V)• 100-265 Vac, >87% typ efficiency

• NCL30083BB1GEVB – 12 W• NCL30082/3 Non-isolated Buck-boost• Intended for A19/PAR/Drivers• 10-20 LEDs at 200 mA (30-60V)• 100-265 Vac, >90% typ efficiency

34.1 X 17.3 X 16mm

Fits in a 22 x 60 mm cylinder

Schematic Change, Different Magnetics6 fewer components

http://www.hztaisun.com/product_detail.aspx?type=21&id=308


NCL30082/3 EVB - Typical Results

190

191

192

193

194

195

196

197

198

199

200

100 120 140 160 180 200 220 240 260

Out

put C

urre

nt in

mA

Line Voltage

29Vout

60Vout

690

691

692

693

694

695

696

697

698

699

700

100 120 140 160 180 200 220 240 260

Out

put C

urre

nt in

mA

Line Voltage

7.6Vout

14Vout

Flyback Schematic, 700 mA setting

Buck-Boost Schematic

78.0%

80.0%

82.0%

84.0%

86.0%

88.0%

90.0%

92.0%

94.0%

100 120 140 160 180 200 220 240 260

Effici

ency

Line Voltage

Buck Boost

Flyback

Efficiency

Current Regulation

0.75

0.76

0.77

0.78

0.79

0.8

0.81

0.82

0.83

0.84

0.85

100 120 140 160 180 200 220 240 260

Pow

er Fa

ctor

Line Voltage

Buck Boost

Flyback

Power Factor


Trends in LEDs

• General trend is to move from high current (350-500 mA) to low to medium current (60-150 mA) LEDs for omni-directional light sources

• Many LED manufacturers are developing High Voltage LEDs• Everlight HV 95-111 V @ 20 mA)• Philips Luxeon H (52 V@40 mA/98 V@40 mA/196 V@20 mA)• CREE XT-E HVW (up to 48 V@ 22 mA) and XM-L HV• Samsung LH934 Series• Seoul Acriche MJT4040 (64 V@ 20 mA) and A5 Series

Since high LED string voltages > 60 V (SELV) level, non-isolated topologies are best suited


Non-Isolated Buck

• LEDs string does not need to be matched to line voltage

• Efficiency can be >85% even at low power (< 4W)

• Does require some design work to optimize

• Low LED current ripple

• Higher parts count and EMI generated so filtering is necessary

Driving Long Strings of LEDs

Linear

• Very simple to design, no EMI generated

• LED string voltage must be matched to input line voltage

• Efficiency and current varies with line & LED Vf

• More LEDs are needed for same light output since LEDs are off for 50% of period

• Large 100/120 Hz Ripple

AC Input240 Vac


Power Factor and Ripple• Linear & buck can achieve high power with some limitations

• 100/120 Hz current output• Inefficient LED capacity utilization, (LEDs are off part of each cycle)• Simplest linear solutions (bridge + resistor) only limits current

• If string voltage is higher than max Vin, boost topology can be used which can achieve high PF and high LED utilization


Constant Current Regulators (CCR) Protect LEDs from Being Overdriven

• CCRs are optimized linear drivers• 2 terminal fixed current

• 10,25,30,40,50,70,350 mA• 3 terminal adjustable current

• 60-100,90-160 mA• Wide packages range from

SOD123 to DPAK• 45 &120V maximum CCR

voltages• 3 120V versions

Product DescriptionNSIC2020B 120 V, 20 mA Constant Current Regulator & LED Driver NSIC2030B 120 V, 30 mA Constant Current Regulator & LED DriverNSIC2050B 120 V, 50 mA Constant Current Regulator & LED Driver


Example: Bridge & 120V CCR

• LED string Vf length• Efficiency• Lumen Output

• Conduction time is the time the LEDs are ON

~VIN

+

-

VAK

ICCR

+-

IF(Total)

VF(Total)

VVV

VVV

PTotalF

MaxAKPTotalF

3)(

)()(

LED Range Conduction Time

P

TotalF

V

V

Ton

)(1sin2

1%

VRMS +/- % VP+ VP- VF(Total)+ VF(Total)- %Ton (Min) % Ton (Max)120 5 178.2 161.2 158.2 58.2 7.77% 78.82%

113.5 12 179.8 141.2 138.2 59.8 8.30% 78.42%220 15 357.8 264.4 261.4 237.8 6.07% 53.72%240 15 390.4 288.5 285.5 270.3 5.81% 51.30%230 +6 / -10 344.8 292.7 289.7 224.8 5.77% 54.79%


CCR + Bridge on Low Mains

• 0.91 PF @ 127 VRMS

• 43.5 % THD• 82% Efficiency @ 127 V

Both designs meet IEC61000-3-2-Class C EN 55022-Class B Conducted < 2% EMI

~VIN

NSI45030AT1G

135V @ 30mA

4 x MRA4003T3

• 0.97 PF @ 100 - 127 VRMS

• 21.1 % THD• 44 % Efficiency @ 127 V

~VIN

NSIC2050

~ 60V @ 50mA

4 x MRA4003T3


Capacitive Drop Addresses Ripple Issue

• The voltage across the capacitor begins to rise as the current flows through the CCR + LEDs• Simply size the R1 and

C value• Limits the voltage over

the CCR to 2 or 3 V.• VERY small form factor• Very high efficiency

4 x MRA4003T3

P

Pg

VfR

VRIC

1

1Re

2

*

R1 = 470kΩ

R2 = 120Ω

Vz = VLED + 4V

More examples and explanation available on www.onsemi.comapplication note: AND8492-D

http://www.onsemi.com/

http://www.onsemi.com/pub_link/Collateral/AND8492-D.PDF


Universal Input Voltage Buck Chopper

MRA4003

NSI45020AT1G

22 LEDs~81 V

22 uF

NDD03N50Z

MMSZ15T1G

MPS4444

32 kΩ

330 kΩ

390 kΩ

MMSZ5260BT1G

2

211 )7.0(

R

RRVVV zo

R1

R2

VZ1

100 – 264 V


NCL30002 Buck Controller

• Hybrid Constant On Time/Peak Current CrM Control• Accurate 485 mV Peak current limit (+/- 3.1% across – 40 to 125 ºC)• ZCD detection to restart switching at zero inductor current

• Low 24 µA typical startup current allows fast startup time

• Integrated error amplifier architecture allows simple line feed-forward implementation to control on-time for power factor correction


Low Ripple

Peak Current/ZeroInductor Current

Restart

Typical PF ~ 0.6Efficiency > 85% @ 4W

Off-the-shelf inductor

High Power Factor

Constant On Time/Peak Current Limit

Typical PF > 0.9 and Efficiency > 90% @ 15W

Based on LED Vf

Two Options for Buck Topology

Input Line Current


NCL30002 Low Ripple Buck

• Charge pump used to provide IC bias after startup• Off the shelf, low cost standard inductors• Low 24 piece bill-of-material count

Input Voltage 200-260 Vac 50/60 Hz

LED Forward

Voltage150 Vdc

Output Current 25 mA dc

Harmonics EN61000-3-2 Class C

Efficiency >85% @ nominal line

Example Design


Current Regulation (150 V LED)


Efficiency at Vf=150 V, 25 mA (nom)


90-135 Vac (120 mA/up to 60 V Vf )

SOT23/SC59 BSS131 FET

7.7 Ω Rdson/240V Vgs

Design Highlights

• ~90% Efficient

• 23 Component bill-of-materials

• Off-the-shelf magnetics

• Example shows Optimization for Japan Market Bulbs


Performance Highlights

125 ms Startup Time


HiPF Buck Application Schematic


Design Guide Worksheet Tool


Example of NCL30002 Driver Design

NCL30002 Demo Board


Non-Dimmable <10 W HiPF Boost NCP1075 Switcher and +/- 2% accurate NCP4328A CCCV Controller

• Off-the-shelf inductor, >91% efficient driving Vf string of 220V @ 30 mA (6.6 W)• Typical PF > 0.96 and THD of <20% at 120 Vac• < 20 msec typical startup time• Perfect for High Voltage LEDs like CREE 48Vx5 XT-E or Philips Luxeon 200 V

Open LEDProtection

CurrentSense

PFOptimizer

Actual Size: 24.1 x 34.7 mm


NCP1075 Boost Efficiency/Regulation

Vout = 213 V (nom)


NCP1075 Power Factor/Harmonic Content

Vout = 213 V (nom)


The NCP4328 consists of two OTA amplifiers providing constant current and constant voltage (CCCV) regulation for switch mode power supplies. It features high accuracy voltage and current references and very low Icc consumption.

• <100 µA supply current• ±0.5% Reference Voltage

Accuracy @ 25 ºC• 62.5 mV +/- 2% Current

sense reference @ 25 ºC

• Improved efficiency

• Tight output voltage and current regulation

• Up to 36 V operating range• Wide temperature range – 40 to 125 ºC

• Available with integrated PWM modulated driver for indication LED for adapters(B version)

• LED Lighting• Notebook Adapters• Battery Chargers• Open Frame Power Supplies

NCP4328 Secondary Side CCCV Controller

• NCP4328A (LED Driver)TSOP-5• NCP4328B (Adapter) TSOP-6

Others Features

Market & Applications

Ordering & Package Information

Overview

Key Features Block Diagram


Summary

• ON Semiconductor has solutions for all low power offline driver topologies• Flyback• Buck-Boost• Buck• Boost• Linear

• Primary Side Control approach optimized for tight accuracy and wide Vf support for high production yield and reduced development time

• General shift in market to address non-isolated topologies


Appendix


Measuring the Leakage Inductor Reset Time

• t1 is measured by monitoring the current in the clamping network.

.

.Vbulk

Cclamp

Rclamp

Rsense

RCS

CCS

CS

Vout

, ,L pk sp leak p L pk

Lleak sp clamp O

I N k L It

S N V V

1 O out fV V V

, , , , , ,L pk clamp O p sp leakt f I V V L N k1

kleak: leakage inductor

coefficient expressed as a part of Lp.


Transformer Design

• Balance between performance and cost of the solution.• Better regulation of the output current if duty-cycle > 50%

• The duty-cycle varies with the output voltage (number of LEDs and input voltage (narrow mains design / universal mains design), thus as a starting point, we can calculate the turn-ratio at the maximum LEDs voltage Vout,max and Vin,min:

.out f

sp in out f

V V

N V V V

0 5

,,

,

.out max f

out max f

spin min

V VV V

NV

0 5


Primary Peak Current and Inductance

• Select the switching frequency Fsw,min at minimum input voltage (including the bulk capacitor ripple) and maximum output load Pout,max.

• Calculate IL,pk and Lp with:

, ,,,

( )

212

2sp out max lump sw minout max

L pkout OVP fin,min ripple

N P C FPI

V VV V

,2

, ,

2 out maxp

L pk sw min

PL

I F

, ( )out max out OVP outP V I


Excel® Based Design Tool

NCL3008X Design Guide Version 4.0

12/5/2012

Input Parameters Calculated Parameters Designer Input Calculated Results

This Design Guide is intended to aid the designer and is not intended as a guarantee of performance.

Line Input Calculated Parameters Maximum Line Voltage 265 V ac Primary Inductance 709 µH

Minimum Line Voltage 100 V ac Peak Primary Current 0.747 A

Line Frequency 50 Hz Secondary Current 0.846 A RMS

Primary Current 0.326 A RMS

Load

LED Vf Min 9 V dc

LED Vf Max 22 V dc Minimum Frequency 55 kHz

LED Current 480 mA dc Maximum Duty Cycle 57%

LED Dynamic Resistance 4 Ω Minimum Duty Cycle 7% See Notes

Ripple Current 50 mA P-P

Peak FET Voltage1 441 Volts

Architecture FET Current 0.326 A RMS

Topology Flyback

Turns Ratio 3 Pri:Sec Peak Output Rectifier Voltage1 147 Volts

Front End Valley Fill

Maximum Switching Frequency 120 See Notes Vcc Rectifer Voltage1 180 Volts

Min Vcc Voltage 11 See Notes

Max Vcc Voltage 26.88888889 See Notes Output Capacitance 21.77 µF

RMS Capacitor Current 0.646 A RMS

Rsense 0.78 Ω

µF

Valley Fill Storage Capacitors 21.12 µF

non-dimmable lower power led solutions

Business

steve west

wide led current vf

vdc startup current

vdc iout

ma source current

voltage protection

low startup current

ma max