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Gate current selection - gate driver chips

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vwdevotee

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gate current

I'm looking at gate driver chips right now, and I'm not sure if I'm forgetting somethign in looking at this. I want a 10kHz minimum switching frequency of the FET, and the FET I'm looking at has about a 1000nC gate charge at 15V. The gate driver has a maximum current of 1A at 15V, so I shoul dbe able to provide the charge needed by the gate in 1000ns or 1µs. Since 1µs is much smaller than the PWM period (100µs) I'm shooting for I should be good, right? Am I missing something here? Obviously I would love to have a charge time in femtoseconds, but will microseconds work? Thanks!
 

vwdevotee

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Gate current selection

OK, so 2A might be a better choice. How did you come to that? If this were the only time I thought I would need to figure thisout I'd go with your recommendation, but for future reference it might be nice to know the engineering rationale behind the choice. I once read the the gate driver curerent needs to be greater than n*f*Q; where n is the number of gates being driven, f is the switching frequency, and Q is the gate charge. While simplae and easy to remember it seems like this could have the gates only partially open for most of their 'on' time. I think my question ultimately boils down to something like 'what's an acceptable switching fraction for a FET or an IGBT?

Thanks a bunch!
 

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