Russell McMahon <apptech@paradise.net.nz> wrote:
> Add a zener to both N & P Channel FETs gate to source of a value
> less than their maximum Vgs but greater than the drive voltage - or
> nasty things can happen due to coupling of switching waveforms into
> the gates.
> 
> The attached circuit can be used for FET gate drive. As shown it's for
> the low side.  You could adapt it for high side but it's not really
> needed if you are slow switching the high side and PWMing only the low
> side. R4 sets the peak gate current which ideally will be 100's of mA
> to amps for fast switching.

Wouldn't it be better to eliminate R4 altogether and put the zener
at the base of Q8? Not only does this reduce the drive impedance to
the FET, it also eliminates the steady-state power dissipation in Q8,
and the zener can be a low-power unit as well.

-- Dave Tweed
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