One way I blew out some FETs was inductance in the source lead. I was
driving the gate with a low impedance (a PIC, of course). When the drain
started drawing current, it appears I got a transient pulse between the
gate and source due to the source being "pulled up". I put a small
resistor (10 to 100 ohms) between the gate and the driver and the problem
went away. Gate capacity then kept the source/gate voltage from changing
too far (over the gate/source voltage limit).

Also, since this is driving a motor, I assume there's a diode across the
motor for when the FET opens, right? Without it, I'd expect the drain
voltage to go real high when the FET opens.

Harold

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