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Old 07-09-2010, 10:23 PM   #13 (permalink)
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Thanks for the reply Mark;

I've read enough about IGBTs to understand what you're talking about, however my controller is using MOSFETs (after three weeks of reading and deciding)

The TVS is a unidirectional 15.2V unit so it should be quite similar to a 15V zener. My max Vgs is 16V so I should be safe there.

I know a lot of people use the 10k pulldown resistors.
Maybe my driver connection came loose and my mosfet went into triode... I don't believe they are as sensitive to that as you say IGBTs are. I suppose I will include it also just to be safe.

Six mosfets down, four to go! Good thing I bought lots of spares :P

Unrelated question: mosfet gate resistors (not pulldown)- absolutely necessary? I have looked high and low; it seems they are chosen empirically rather than actually calculated. My circuit seems to want a very low gate resistance. Maybe I should have chosen a more powerful gate driver? I don't really understand the tradeoffs here.
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