Re: Chopper circuit

--- In CAD_CAM_EDM_DRO@y..., Steve Blackmore <steve@p...> wrote:

> Here's the link to my 3 amp Bipolar chopper driver board.
> http://www.pilotltd.net/chopper2.zip
> It contains the schematic, and PCB overlays.
> Comments please!
> Steve Blackmore

Hi Steve,

Schematic looks good. The only wmf that I could
get to open was the composite and it was not
possible to understand layout using that.

Comments:

1) Keep in mind that the logic supply load on
your board will be around 100 mA. If, for
example, you intend Vs to be 35 volts; then
the power dissipation in the 7805 would be
(35-5)*0.100=3.0 watts, enough to need a
heatsink. Vs input above 35 volts would
exceed the maximum allowed input voltage for
the 7805 regulator.

2) It would be nice if the control signals to
the L297 had pull up resistors so that you
would have know operating conditions if the
signals were not driven.

3) Don't forget that the diodes on the motor
outputs need to be fast, usually schottky
diodes.

4) Paralleled section L298's can operate at up
to 3 total amps continious, not twice the 2
amp rating of the regular configuration.
I think this was mentioned before, but didn't
want it to get overlooked. Operating at 3
amps the L298 will probably dissipate around
5 watts, again enough to require a good
heatsink.

Good luck,
Steve Stallings