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Subject: Re: Unipolar stepper motor driver wiring

From: "Phil" <phil1960us@...>
Date: 2005-06-22

--- In Homebrew_PCBs@yahoogroups.com, "Roy J. Tellason"
<rtellason@b...> wrote:
...
> This is the second post I've seen so far that seems to suggest that
it's okay
> to rely on the internal diodes in mosfets. The general consensus in
other
> lists seems to be that this is _not_ a real good idea, for a number of
> reasons. One of those is that those internal diodes don't have very
> consistent characteristics, and another is that they turn on too
slow, and
> turn off too slow, which will tend to make the device run hot.
Since heat
> is an enemy of semiconductors, I'd tend to go with the external
diodes,
> myself.

agreed. even if they switched fast, there would be dissipation IN THE
MOSFET. Distributing the heat dissipation is a good thing.