On Sat, 12 Oct 2002, Jinx wrote:

*>> *>High reverse voltage schottkys generally have higher forward drop,
*>> so if *you can choose lower voltage ones, do it. But they'll always have
*>> a lower *>drop than the diode in the FET.
*>>
*>> Why not sense reverse voltage drop across FET diode and turn the
*>> FET on with an opamp that overrides the bridge driver ?
*>>
*>> Peter
*>
*>Are you saying use the FET to soak up the back EMF that the diodes
*>would have ?

Yes. The FETs conduct backwards just fine when driven on. This is what is
used for active rectification. Since this is a first project you should
use conventional techniques imho ...

The conducting FET trick I've seen used in non-PWM bridge drivers where a
large inertial load is attached (small electric vehicle). Maybe it would
work with PWM but it would have to be fast. Usually higher power
electronics tend to go down in frequency.

Peter

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