On Sat, 26 Feb 2005, Wouter van Ooijen wrote:

>> Your N-channel MOSFETs are being forcibly and rapidly turned off
>> by the ULN2003s but the P-channel MOSFETs are only being turned
>> off by the 4K7 gate-to-source bleeder resistors, which cannot
>> remove gate charge very fast.
>
> That's sounds OK, but I knew this so in PWM mode the P-FET is on all the
> time, only the (opposite) lower N-FET is switched! And more bizarre: it
> is not the P-FET that is on (conducting) that gets hot, it is the other
> one, who is supposed to be off!

Probably its bulk diode conducts in reverse while the N-FET below it 
turns off ?

Peter
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