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This is my first time posting here. I want my device to pass the Low voltage directive testing and that includes ESD stuff.

So as you can see below, my device is Li-ion charger with isolated PSU.

enter image description here

The question: Where should I put the ESD diodes(like ESD9B3.3ST5g or PGB01 series)? At the moment I think they should be connected as in the image. Data or power supply pins - TVS - mains ground.

I have read several topics regarding connection of grounds and it seems kinda messy, everyone has their own opinion and I can't really decide what is the best solution.

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  • \$\begingroup\$ I'm hardly an expert in the area but what you have seems logical to me. You want to dump the ESD energy directly to the mains ground, that's where it's trying to get to. \$\endgroup\$ – Andrew Jan 9 '17 at 14:15
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The ESD9B3.3ST5G is a dual back-to-back zener.

For positive ESD voltages this will clamp to about 11 volts so it's possible that this may be too high to adequately protect your circuitry. Also, given that it does the same in reverse (i.e. -11 volts) then this could indeed by too high in magnitude to offer any protection when the ESD is negative.

I suggest you read the data sheet for the device and for the connected chips inside what you call "Li-ion battery charger" and do a full analysis.

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