MOSFET gate protection

I think it's best if you post a schematic. You'll have some series R too, I trust.

George H.

Good practice indicates a use of back-to-back zener; protecting gate from over-voltage either polarity. 12V gives some safety margin as most MOSFETS seem to be rated at 15V.

Two points: First, for n-channel MOSFETs, generally we don't drive them negative, so a single ordinary zener works well. Second, most mosfets are rated at 20V, and 12V drive is often specified, so a 15 or 16V zener would be better as a rule than 12V.

Or a 20 volt zener, to minimize the likelihood of blowing out the zener. Most mosfets stand a lot more than the rated gate voltage.

A series resistor is a good idea too, if speed allows.

Of course, "good practice" is a waste unless you actually expect gate transients.