Mohit Mahajan wrote:
.
> Actually the peltiers are driven by an H-bridge, so that they can cool
> or heat (user menu driven). The DC-DC converter I'm trying to build will
> power the H-bridge. The H-bridge will only reverse the voltage across
> the peltiers. No PWM here. Because if there was PWM in the H-bridge I'd
> have to do the filtering there, with capacitors across peltier and to
> ground that could take voltage both ways. I'm really not able to
> (easily/cheaply) find large value ceramic capacitors suitable for such a 
> filter. I'm also not comfortable with reversing voltage across
> capacitors even if they were ceramics.

You should really look at how other people do it, and not reinvent the
wheel. Doing PWM with the H-bridge is the right way. After the H-bridge,
use two inductors(or a dual inductor) and two capacitors. Each capacitor
returns to ground, so it does not need to be bipolar.

You mentioned the TC4420 driver, those are good. If you get the one with
both input polarities it's easy to wire them to logically prevent
"both-on" situations.

I think either Maxim or LT have documents about Peltier drivers to
support their specialized parts. Although I am not recommending their
parts, I do recommend you read their documentation and look at their
component and topology choices.

Cheerful regards,

Bob
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist