>-----Original Message-----
>From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] 
>Sent: 27 June 2006 13:30
>To: Microcontroller discussion list - Public.
>Subject: Re: [EE] Peltier Device Info wanted.
>
>
>
>Maxim app note mentions only efficiency loss with ripple
>
>" ... . Because current ripple above 3% degrades the TEC's cooling 
>efficiency, a high switching frequency is recommended for easy 
>filtering of the AC components. "
>
>        http://www.maxim-ic.com/appnotes.cfm/appnote_number/1757/

>From http://www.marlow.com/TechnicalInfo/frequently_asked_questions_faqs.htm (one of the big TEC manufacturers)

"Thermoelectric coolers require smooth dc current for optimum operation. A ripple factor of less than 10% will result in less than 1% degradation in delta T."

I guess the issue is wether 1% reduction in delta T is significant in Alans application.

The thermal cycling effects are only significant at very low switching fequencies (e.g. bang-bang control).  The thermal time constant of even a very small TEC is of the order of a second or more.  A reasonably well filtered switcher operating in the kHz region should not cause problems in this area.

Regards

Mike

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