Hello,

I am designing a peltier heater/cooler using PWM (10kHz, 12VDC @ 8A)
and an H-bridge. To filter the ripples across the peltier, I plan to
use an LC filter:

                        ____ Peltier
                   ----|____|----
                   |            |
                   |            |
               L   |       C1   |   L
              ___  |     ||     |  ___
       V+ o---UUU--o-----||-----o--UUU---o V-
                   |     ||     |
                   |            |
                   |            |
               C2 ---          --- C2
                  ---          ---
                   |            |
                  ^^^          ^^^
                  GND          GND

(created by AACircuit v1.28 beta 10/06/04 www.tech-chat.de)



C1, C2, C3 values are 10uF.

I am able to get multi-layer ceramic capacitors 16V,10uF in SMD1210
package from Kemet/Murata. I have a few questions regarding these...

1. How much should I derate these capacitors for my use? Is 25% okay
(12V PWM over 16V)? The dielectric is X7R.
2. Are these suitable for use in filters in an 8A application? Or
should I be paralleling them to increase the current?
3. Are there any other types of capacitor (SMD or otherwise) that can
be used here (without polarity, ~10uF and 8A)? Are metalized
polypropylene caps suitable for filter circuits?
4. If not, can anybody suggest alternate filtering methods for peltier
coolers? The manufacturer (and past discussions on this list) say less
than 10% ripple across the cooler.

Thanks,
Mohit.

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