Need an analog driver for a big mosfet. Not sure if there might be an appropriate power op-amp out there or not. Linearity is not too important as long as I can drive the mosfet to different pulse amplitudes. Seems that most mosfet drivers are digital. Right now I'm considering a wimpy op-amp driving a PNP/NPN pair. The mosfet itself would be a IRFZ44 or similar. I'd like to get a rise-time on the gate down to a few uS.
Thanks, Dave
What's the peak current requirement work out to be?
How about four sections of a quad opamp? Run them as followers, with each having a, say, 100 ohm resistor to the gate.
John
Usual technique is to use an NPN/PNP complementary pair driving the gate. Watch out for driver dissipation btw.
Graham
How about an LT1206 with the capacitive load compensation connected?
It will drive about 250mA. The overshoot and ringing issues normal to driving capacitive loads are taken care of.
-- -- kensmith@rahul.net forging knowledge
Yeah I wonder. Seems like there are numerous approaches. I guess I'll have to experiment. Thanks.
Can anyone offer a reason why slower rise-times might be seen at the output of a power FET being turned on only partially? I 'm trying to diagnose the issue remotely, so I don't have it in front of me, but it doesn't make sense. I can't see why it would ever take a driver circuit longer to drive a FET to produce 5 amp pulses than to produce 30 amp pulses. Am I forgetting some devious issue?
Thanks, Dave
I read in sci.electronics.design that Dave wrote (in ) about 'Analog MOSFET Driver', on Mon, 7 Mar 2005:
If Rds,on = 2 ohms, you get a delay of half a mho. (;-)
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