System level transient voltage protection

The challenge of protecting today’s systems from transient threats is more complex than ever before. As semiconductor manufacturers introduce new wireline transmission devices built on smaller CMOS geometries, more circuit protection challenges are emerging. CommsDesign article System level transient voltage protection–Five in-depth answers to ESD questions gives answers to important questions that can ensure that a system is adequately safeguarded against these damaging electrical transient threats. This article explores five frequently asked questions regarding the basics of ESD and transient voltage suppression for board level circuit protection on dataline communication circuits.

Currently, most electronic equipment manufacturers recognize the tradeoffs, understand the value of time to market, and opt for using good low-clamping off-chip protection to safeguard their systems from electrical overstress. Several different ESD immunity standards are used in the electronics industry, each one describing appropriate immunity levels for the intended ESD environment. IEC61000-4-2 describes and models the ESD threat level encountered at the system environment with fully packaged ICs operating in a complete electronic system.

There are many devices on the market for transient voltage protection with different specifications. It’s unfortunate, but transceiver IC datasheets (the devices that need to be protected) generally do not provide transient voltage immunity ratings. A good layout is very critical for transient protection performance. Even a very good protection circuit may not overcome a poor layout.