modified 6 years ago

MOSFET Gate Drive Problem

01:17:37

mosfets have capacitance on the gate.  this means you can't drive them directly using cmos gates or you'll cook the outputs. 

in this example I've got a 2SK3262 N MOSFET being driven by a logic gate.  the ammeter shows the current required to charge the gate to 5V is 23mA; well above the rated source current for the gate output.   the faster the rise time of the signal, the more current gets sourced.

fixes for this:
- use a longer rise and fall time (which reduces switching frequency as well). 
- use a gate drive transistor pair. 
- use TTL instead of cmos

published 10 years ago

flowDAQ

10 years ago

And a body diode which means an N-CH source must be tied to the low side as faceblast shows.

faceblast

10 years ago

added a diode

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