When should ESD Protection Diodes be used?

Question

I'm working on a heated glove project that uses a Buck-Boost converter to step-up/step-down the voltage across the heating element. This is something that has just occurred to me, but I'm not sure if my fabric will cause any ESD issues. The fabric itself will be sewed to a polyester glove liner inside a fleece glove, so ESD may or may not be present. The PCB itself will be coated with a conformal silicon coating and placed into the inside padding of the glove, but I feel that the DC/DC converter IC could still get damaged from possible static of the fabric discharging into the output pin of the IC.

So would this be a situation where a ESD diode should be used? And if so, should it be used with a DC/DC converter?

Answer 1

The DC-DC has a very low output impedance due to its filter capacitor, so it’s not likely to be vulnerable to ESD.

ESD protection is generally applied to signals that go to the outside world. Sometimes it’s used on external power inputs too as a precaution. Your heated glove isn’t either one of those.

Answer 2

The output of the converter may be low impedance, but AFAIK there's no reason to assume it's going to be operational when the glove is being put on. The IC probably has some limited protection, and the output cap and inductor will protect it to an unknown degree, but I always like to err on the side of caution when it comes to ESD. If there's a user accessible battery or charger port, I'd consider protecting those as well.