1 Version01_ Introduction to TVS Diode Arrays (SPA TM Family)  Purpose –To introduce Littelfuse’s TVS Diode Arrays (SPA TM Family) for ESD and Lightning Protection  Objectives –Discuss the various threats that can affect electronic devices and the standards used to evaluate their performance –Explanation of how protection devices operate –Discussion of key parameters commonly found in datasheets –Explanation of why silicon is the preferred protection technology –Examine the Littelfuse TVS Diode Array portfolio and how the products are categorized

2 Version01_ ElectroStatic Discharge Protection ESD is one of four major threats to electronic equipment and is the direct result of human interaction. Lightning AC Power Contact Sustained Overload

3 Version01_  Triboelectric charging occurs when two materials make contact and separate  Electrons from one material are transferred to another leaving one positively charged and the other negatively charged. –The nature of the materials will determine who losses or gains electrons  The build up of static electricity is determined by several factors such as: area of contact, the speed of separation, relative humidity, and chemistry of the materials, surface work function, etc. *Table from ESDA What is ESD and where does it come from? – Triboelectric Charging

4 Version01_ ESD Standards – Human Body Model, MIL-STD  Based on Skin-to-Metal Contact –e.g. Person touches pin of IC, discharging directly to pins  Referenced in the Military Standard (883, Method ) test specification  Addresses the Manufacturing/Production environment; testing is done directly on the IC  Circuit Model: VoltagePeak Current 500V0.33A 1,000V0.67A 2,000V1.33A 4,000V2.67A 8,000V5.33A

5 Version01_  Based on Metal-to-Metal Contact –e.g. Person with tool/key in hand discharges to I/O port  Used in IEC test specification  Addresses the user-environment; testing is done at the application or system level  Circuit Model: Voltage Peak Current 2,000V7.5A 4,000V15.0A 6,000V22.5A 8,000V30.0A ESD Standards – IEC

6 Version01_ Discharge Voltage First PeakCurrent, 30nsCurrent, 60ns 2,000 V 7.5 A 4 A 2 A 4,000 V 15.0 A 8 A 4 A 6,000 V 22.5 A 12 A 6 A 8,000 V 30.0 A 16 A 8 A Specified current values, per discharge voltage Most all manufacturers test to 8kV or higher! ESD Standards – IEC Waveform

7 Version01_ Peak current Discharge VoltageHuman Body ModelIEC V 0.33 A 1,000 V 0.67 A 2,000 V 1.33 A 7.5 A 4,000 V 2.67 A 15.0 A 8,000 V 5.33A 30.0 A  The key here is that a chipset that survives Human Body Model testing (in the manufacturing environment) is not guaranteed to survive in the field, where the exposure to ESD will be much more severe.  Different models yield much different peak current values; ultimately electrical stresses on the chipset are very different.  ESD levels in the field far exceed the values that can be generated in the manufacturing environment. Comparing the Two Specifications – IEC vs. Human Body Model

8 Version01_ TVS Diode Arrays for ESD and Lightning Protection  Generally, 2 circuit types  TVS Arrays  Typical capacitance range 3.5pF-30pF  ESD Level: ±8kV to ±30kV  Can be unidirectional or bidirectional  Diode Arrays  Typical capacitance range 0.40pF-5pF  ESD Level: ±8kV to ±30kV  Can be unidirectional or bidirectional  Sizes range from 0201 to MSOP-10  Operating voltage up to 6V DC  Number of channels range from 1-14

9 Version01_ Time Voltage Transient ESD Circuit Damage Level Clamping Level Normal Operating Level TVS Diode Arrays How do they work? GND

10 Version01_ Time Voltage Transient ESD Circuit Damage Level Normal Operating Level TVS Diode Arrays How do they work? GND Energy Dissipated in TVS Clamping Level

11 Version01_ BidirectionalUnidirectional TVS Diode Arrays What are the key parameters? +I +V -V -I I PP I T V R V BR V C I R +I +V -V -I I PP I T V R V BR V C I R +I +V -V -I I PP I T V R V BR V C I R +I +V -V -I I PP I T V R V BR V C I R

12 Version01_ I +V -V -I I PP ITIT V R or V RWM V BR VCVC IRIR Key Parameters: V R or V RWM Reverse Standoff Voltage or Reverse Working Maximum

13 Version01_ I +V -V -I I PP ITIT VRVR V BR VCVC IRIR Key Parameters: V BR Breakdown Voltage

14 Version01_ I +V -V -I I PP ITIT VRVR V BR VCVC IRIR Key Parameters: V c Clamping Voltage

15 Version01_  Peak Pulse Current (Lightning Capability)  For protection of telecom or broadband equipment lightning immunity is just as important as ESD protection so for these devices the peak pulse current can be the driving factor.  The required level is often driven by regulatory standards such as Telcordia GR-1089, ITU, YD/T, IEC, etc  Common waveshapes (t r xt d ) are 2x10µs, 8x20µs, and 10x1000µs Key Parameters: Peak Pulse Current (I PP )

16 Version01_  The figure below depicts a protection device as a variable resistor which will be high impedance (low leakage) during normal circuit operation and low impedance during any EOS (Electrical Over Stress) or ESD event.  The ultimate goal of a protection device is to provide the lowest resistance shunt path to GND under an ESD event to minimize the energy seen by the chipset or IC.  Ideally, all current would be steered into the ESD device so that the protected IC would not have to dissipate any of the energy input into the circuit.  Lower R DYN = Lower clamping voltage = Better, more robust protection Key Parameters: Dynamic Resistance (R DYN )

17 Version01_  The dynamic resistance is the impedance value that the ESD suppressor represents as it switches from “off” to “on”  Using SP WTG as an example, we find:  This is the single best parameter to use in comparing ESD suppressors to determine which one is better! Dynamic Resistance How it’s calculated

18 Version01_ Peak Voltage = 240V vs. 156V Clamp Voltage = 75V vs. 16V  Data of Littelfuse’s SP DTG vs. a competitor varistor. Both devices have the same footprint (0402), same standoff voltage, and similar capacitances. The area between the curves represents the amount of energy that DOES NOT get to the chip when this MLV was replaced by the SP DTG. The reduction in transient energy helps ensure that the chipset will survive even severe ESD events. Dynamic Resistance Comparison of Competing Technologies

19 Version01_  Capacitance  Low capacitance is needed in high-speed applications to minimize signal degradation  A low capacitance device ensures the eye-diagram can stay within spec to prevent data corruption Key Parameters: Capacitance

20 Version01_ General Purpose ESD Protection Low-speed circuits (< 100Mbps) Examples include power ports, keypads, buttons, switches, audio, analog video, USB 1.1 Low Capacitance ESD Protection High-speed data buses (> 100Mbps) Examples include HDMI, USB 2.0, USB 3.0, FireWire, DisplayPort, Ethernet, eSATA Lightning Surge Protection Specifically refers to Ethernet (10/100/1000) and xDSL circuits in which there is a requirement to provide ESD and/or lightning surge protection (will vary by standard, customer, and application). TVS Diode Arrays Product Categories

21 Version01_ General Purpose ESD Protection Low Capacitance ESD Protection Lightning Surge Protection SP05SP1001SP1002 SP1003SP1004SP1005 SP1006 SP1007SP1010 SP1011 SP720SP721 SP723 SP724SP725 SP6001SP6002 SP3001SP3002SP3003 SP3004SP3010SP3011 SP3012 SP03-3.3SP03A-3.3SP03-6 SPLV2.8 SPLV2.8-4SP3050 SP4060SP4061SP4062 SP4040 TVS Diode Arrays Product Categories

22 Version01_ System Level ESD Guide  Available on the Littelfuse website: –  Discusses multiple applications such as: –USB1.1/2.0/3.0 –HDMI –DVI –10/100/1000 Ethernet –eSATA –1394a/b –LVDS –Audio (Speaker/Microphone) –Analog Video –SIM Sockets –RS-485 –CAN Bus –Keypad/Push button –LCD/Camera display interfaces

23 Version01_ Introduction to TVS Diode Arrays (SPA TM Family) Thank you!