The datasheet of C3M0065090J says its VGSmax is -4/+15V, but Note (2) says the "MOSFET can also safely operate at 0/15V." What is "safely" supposed to mean? As safely as a Si MOSFET with no negative gate voltage? Could you please share your opinion on SiC device driving based on your actual experience?
Best regards, Piotr
I'm driving the Cree parts at +20 and -6, pulsing real fast, in the 10 ns pulse width range at over 1KV. If you don't need to go as fast, you can probably do fine without driving the gate negative. We found that negative swing speeds up the switching edges.
Running at high frequency, negative swing will speed up turn-off and overcome Miller feedback and reduce switching losses. What's your frequency?
I blew up some Crees driving the gates too hard. They are serious about the Vgs-max numbers.
A little series inductive peaking helps too, to critically damp the actual internal gate pulse. SiC fets tend to have more internal gate series resistance than mosfets; some are terrible. That's probably why the negative gate swing helps.
We had to make our own gate driver circuits to slam the Cree gates really fast, amps per nanosecond. Can't show that.
The substrate diodes, and their Spice models, are awful.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement
We noticed that. I think there's a lot of automotive use.
ST has some nice SiC fets. OK Rds-on but an impressively flat tempco of same, so they beat the Crees at high current.
The SiC chips are tiny, so cooling is a problem. Thermal runaway from the Rds-on tempco is possible in the Crees.
That's a C2M0280120. Putting that tiny chip in a TO247 package is kind of silly.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement
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