Power supply is 50V. Power into the DRV8302 PVDD1 and PVDD2 is protected by a ferrite choke and a 55V zener.
I am running 6x 100nC Qg FETs and switching all of them at 30kHz. 100E-9 x 6 x 30E3 = 18mA. Once I get to 25-35% duty cycle and a little over 60A motor current, the DRV8302 GVDD fails and stays <=1.7V until I replace the DRV8302. This is very repeatable. Under no load, I can spin the motor to 100% duty cycle with no problems. Don't know why motor load would affect gate drive power. There could be a clue there.
DRV8302 datasheet page 13 says "The three-phase gate driver can provide up to 30 mA of average gate driver current. This can support switching frequencies up to 200 kHz when the MOSFET Qg = 25 nC"
So either the GVDD <= 1.7V is a symptom of something else broken (everything else seems to be OK) or the regulator is breaking when it shouldn't break. 25nC switching at 200kHz means my 100nC switches should work at 50kHz.
I suspect that 30mA number should be specifying a total power dissipation in the regulator ie 30mA@ 30V PVDD1 means Ptot GVDD = .6W. I'm dropping 40V across GVDD regulator so that would put my limit at 15mA, if my suspicion is correct. Can anyone verify this?
