How to design ESD protection of sensitive devices?

[LauraCx]

How to design ESD protection of sensitive devices?

0. Summary
This article answers some Frequently Asked Questions about ESD protection of sensitive devices. 
1. What would you recommend for clothing when handling ESD sensitive
devices?
In an ESD-controlled environment, a conductive lab coat with ESD wrist connected to the ground are recommended.
2. Can you tell something about protection during soldering (ie: solder connector
wires to a board)?
During soldering (connector as example), only HBM is relevant but the environment must be under control (operator with wrist connected to ground, solder iron connected to ground).
3. Can TVS diode and Zener diode be in parallel (Zener to protect from DC
overvoltage and TVS to protect from transients)?
TVS protects against transient over-voltage while Zener is for voltage regulation, because not rated against surges nor over-voltages. To protect against DC over voltage, an over-voltage protection (OVP) is required. OVP and TVS can be used together with TVS maximum clamping voltage slightly below OVP AMR.
4. Can I use a Zener diode to clamp an ESD over-voltage?
A Zener diode is used for voltage regulation under DC-current condition but neither their silicon nor their package is rated for transient surge dissipation.
Only ESD or transient voltage suppressor (TVS) specify the transient surge they can dissipate.
5. Do I need additional ESD protection if I use digital isolators for I/Os (like
Si86xx)?
Yes, this specific product requires an external ESD protection. For 1 Mbps signal with 5.5 V AMR, we recommend USBLC6-2SC6 or USBLC6-4SC6 according to the number of lines to be protected.