1 Confidential and Proprietary to Littelfuse, Inc. © 2007 Littelfuse, Inc. All rights reserved.

Consumer Electronics SPA Training

Training Agenda

– Silicon Protection Array Definition and Circuit Protection

– Silicon Protection Array Basic Characteristics and Related Physics

– Typical Silicon Protection Array Types and Related Segments

– Silicon Protection Array Selection Concepts

– Littelfuse Silicon Protection Array Brands and Future Development

– Frontiers of Silicon Protection Array Technology

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Consumer Electronics SPA Training

Silicon Protection Array Definition

– Silicon Protection Arrays are protection ICs with an array of semiconductor structures for ESD and over-voltage protection of sensitive input circuits.

– SCR and TVS technology is utilized in the LF diode array devices.

Circuit Protection Concepts

– Need to protect against ESD threats to sensitive ICs and other components

• Human body generated

• Environmental (non-human)

– Regulatory requirements related to circuit protection

• IEC 61000-4-2

• HBM (MIL-STD-883D, Method 3015)

• ANSI/ESD SP5.1.1

– Method of Circuit Protection

• Line to ground, line to line, and rail clamp configuration to fit various protection needs

• ESD voltage transient clamped to 10 Volts or less

• SOT23, SC70, SOT5xx, SOT9xx various packages to meet stringent board space requirements

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SPA and Consumer Electronics Circuit Protection

Silicon Protection Array Definition

– Silicon Protection Arrays are protection ICs with an array of semiconductor structures for ESD

and over-voltage protection of sensitive input circuits.

– The LF SP7 series protection arrays are rail clamp type devices. They have 2 protection

SCR/Diode device structure per input. The number of available inputs varies from 2, 4, 6, 8,

16…depends on the design. Also, multiple protection cell structures could be paralleled for a

single input to enhance ESD withstanding capability.

– The LF SP5 series protection arrays are Avalanche type devices. They have one avalanche diode

device structure per input. The Anode of the avalanche diode is connected to ground. There may

be arbitrary number of inputs available for each diode array device.

Protection diode array Input connection Protection IC structure

SP7 Rail Clamp SCR

SP5 Rail or Line Clamp Avalanche and/or Steering Diode

Low cap. SPA Line Clamp Avalanche and Steering Diode

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SPA and Consumer Electronics Circuit Protection

ESD Threats in Consumer Electronics Systems

Besides short circuit and overload conditions, interference susceptibility is a common and major

threat to the consumer electronics. The IEC 61000 standard has categorized this threat as the

follows:

– "Soft" failure

• Data corruption or system latch up

– Latent damage

• The circuit is still functional, but components have been damaged and can degrade with time

or have a shortened life span. A typical result is increased leakage current.

– Permanent damage or Catastrophic failure

• Junction burnout

• Oxide punch-through

• Melted trace

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SPA and Consumer Electronics Circuit Protection

ESD Modeling - Human Body Model

ANSI/HBM Model

•Based on Skin to Metal Contact Method

•Used in Military Standard for ESD Events

IEC Model

•Based on Metal to Metal Contact Method

•Used in IEC 61000-4-2 Test Standard for

ESD Events

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SPA and Consumer Electronics Circuit Protection

IEC 61000-4-2

• Most commonly referenced standard

• CE Marking certifies compliance to testing to 61000-4-2 guidelines

• Most severe, in terms of current delivered to DUT

• “Pass” is achieved if system suffers no upset or damage

• 10 pulses are applied to the Device Under Test, in the polarity that the DUT is most sensitive to

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SPA and Consumer Electronics Circuit Protection

Silicon Protection Array Advantages as ESD Suppression Device

• Provides most reliable clamping protection

– Compared to other available over-voltage protection technologies such as GDT, MOV, and

PGB, the Bipolar structure of the SCR and Avalanche protection arrays will not degrade over

time (when the ESD pulse is within the device surge rating).

• Lowest clamping voltage

– The SCR rail clamp voltage is determined by the VBE of the internal SCR structure which is

less than one volt.

– The Avalanche line clamping voltage is determined by the internal avalanche voltage which

could be on the order of 5-7 Volts.

• Offers various types of packaging and multiple input lines

– Offers IC chip design versatility and wide availability of the IC package styles

– Extremely adaptable to the smaller product packaging requirements and multi-line schemes

of today's cell phone, pocket PC, and other consumer handheld electronics

• Fast response time

– Both the SCR and Avalanche protection structures of the LF protection arrays offer fast

response speeds in the measure of pico seconds.

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Consumer Electronics SPA Training

Section 2 Silicon Protection Array Characteristics and Device Physics

Basic Silicon Protection Array Characteristics

– Electrical Characteristics

• Trigger voltage

• Clamping voltage

• Response time

• Leakage current

– Maximum ratings

• Continuous / Transient

• ESD Pulse withstand

– Thermal Characteristics

• De-rating

– Signal Integrity Characteristics

Silicon Protection Array Construction and Related Performance Characteristics

– Array structure vs. electrical characteristics

– Array structure vs. Maximum ratings

– Array de-rating and physics

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SPA Characteristics and Device Physics

Electrical Characteristics

SCR Type Devices:

The V+ and V- supply voltage may be changed

to suite the needs of the circuit under

protection.

The range of the voltage may be power supply

levels ranging from 4.5V up to 35V.

Input Capacitance is about 3pF.

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SPA Characteristics and Device Physics

Electrical Characteristics

Avalanche Type Devices:

Power supply voltage is not required.

The voltage can range from 0V-7V before

breakdown.

Input Capacitance ranges from 1pF to

100pF.

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SPA Characteristics and Device Physics

Device Construction

The construction of an SCR Type array Equivalent SCR circuits of the protection cells

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Consumer Electronics SPA Training

Section 3 SPA Consumer Electronics Applications Examples

Typically used for ESD protection of extremely high-speed data lines

– Keyboards/keypads

– S-video output

– RS 232 (serial) ports

– IEEE 1284 (parallel) ports

– USB 1.1 (serial) ports

– 10BaseT Ethernet

– 100BaseT Ethernet (depending on system capacitance)

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SPA Consumer Electronics Applications Examples

Application of SCR Type Array

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Diode Array Consumer Electronics Applications Examples

Protected

circuit

SP0503BAHT

Application of Avalanche Type Array

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SPA Consumer Electronics Applications Examples

Global Lab Capabilities • Qualification of all LF products

• UL-Approved Customer Testing in ISO 17025 Lab (Des Plaines)

– High power (AC/DC up to 1KV/50KA) UL approvals available in DP

– Telcordia approvals in DP planned (2008)

• Verification of Telcordia, ITU, IEC, FCC, and other industry, regulatory, and safety standards

– Verification to various OC and OV standards

• Insure application meets standards before submitting for approval

• Customer Application testing

– Assistance with design-in and performance verification

• Help with selection of appropriate technology and rating

– Application troubleshooting

• Assistance insuring proper OV/OC and primary/secondary protection coordination

– Competitive evaluations

• Competitive or technology performance comparisons

– Reliability & Tin Whisker data/testing

Typical IEC 61000-4-2 ESD Waveform Response for

V5.5MLA0603 @ 15KV Contact Discharge (Enlarged View)

-50

50

150

250

350

450

550

650

-4 1 6 11 16 21

Time (nsec)

Vo

lta

ge

(vo

lts

)

V5.5MLA0603

TestBoard

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Consumer Electronics SPA Training

Section 4 Diode Array Consumer Electronics Application Product Selection

– SPA Feature comparison

– SPA Circuit Protection Techniques

• Basic diode operation

• TVS diode array protection

• Rail Clamp diode array protection

– SPA board Placement

• Must be placed close to I/O interface

• Must be placed directly between the dataline and the chassis ground

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Feature Comparison

Avalanche Diode vs. Rail Clamp

Parameter Avalanche Diode

High Voltage

Rail Clamp

Low Voltage

Rail Clamp Comments

Capacitance (pF) 30 - 39 3 - 5 0.8 - 5 Key factor in selection

Power handling ESD Only *

ESD, EFT and

Lightning ESD Only * Driven by absorbed power

Input Polarity Unipolar / Bipolar Bipolar Unipolar Refers to normal input signal

Transient Protection Bi - Directional Bi - Directional Bi - Directional

SPA Product Selection

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Input terminals are connected to the

signal lines requiring protection

SP Series TVS Avalanche Diode Arrays

Protected

Circuit

“Positive”

Transient

Once the reverse standoff voltage

has been exceeded, the diode

conducts and the transient is

clamped.

SP0503BAHT

SPA Product Selection

19 Confidential and Proprietary to Littelfuse, Inc. © 2007 Littelfuse, Inc. All rights reserved.

Input terminals are connected to the signal lines

requiring protection

“Lower Pair”: Clamps at 0.7V below V-

“Upper Pair”: Clamps at 0.7V above V+

SPA Product Selection

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Consumer Electronics SPA Training

Section 5 SPA Product Road Map

Variant Surge (kV) Cap (pF)

SP 7xxx 4 3

SP 05 20 30

SP 05 8 8

SP LC 05 8 0.6

SP LC 05 15 1.2

21 Confidential and Proprietary to Littelfuse, Inc. © 2007 Littelfuse, Inc. All rights reserved.

Consumer Electronics SPA Training

Section 6 Consumer Electronics Diode Array Technology Challenges

– SPA Trigger Voltage

– SPA Clamping Voltage

– Higher Surge Ratings in Smaller Packages

– Greater Multiple Line Protection in Smaller Packages

– SPA Technology Combined in Same Package with other Technologies

– Higher Operating Temperatures