On 03/02/2011 17:00, Wouter van Ooijen wrote:
> lousy 2.5V at 1A, so this is not a very good diode, but this is within
> the "normal operating condition" for this chip. Of course, if you think
> 2.5V is way too much, or you fear you will exceed the maximum power
> dissipation of the chip, or you are afraid these diodes will be too slow
> (I see no switching time info), external (better!) clamping diodes might
> be a good idea (as shown on page 6), but basically this chip has
> internal clamping diodes.

All what he says and:

For clamping, Fast and current rating may be more important than=20
Schottky. Schottky is more important for series diodes in normal current=20
path, especially in low voltage high current PSUs.

Also you may want Snubber Network at Motor connections to reduce rise=20
time and initial peak current.

A reasonable overview
http://en.wikipedia.org/wiki/Snubber

On a Bridge driven motor you might put four diodes (ground to out1, out1=20
to Vs, ground to out2, out2 to Vs) on the PCB, but have transorb (back=20
to back zener rated more than supply volts) and/or R & C snubber network=20
to reduce RFI and current in cable to the on-board diodes. You might=20
have transorb at 1.5 to x3 the supply volts. Power rating of C and R may=20
be important! Many years ago a I saw C explode when large motor 1st=20
turned off.

A stepper or any multiple winding motor is a more complex issue as=20
explained earlier.
--=20
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