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Subject: Re: Pelitier Device? (cooling an IC)
Date: Mon, 23 Dec 2002 21:58:05 +0000
NNTP-Posting-Date: Mon, 23 Dec 2002 22:14:40 +0000 (UTC)
X-Newsreader: Turnpike Integrated Version 5.01 S <8dnav0hwj7jPmXaT+661Vrr+8M>
In article , Jim Stockton writes
>> I am looking for information on a device that uses electricty to cool an IC.
>> The device is called a Pelitier junction, if memory serves. I've tried
>> spellings on a google.com search without finding any specific technical
>> information. Maybe my spelling is THAT bad! (Wouldn't be the first
>> time...won't be the last!)
>> I need to find out if they work in a hot environment. I have an application
>> where a microcontroller will need to operate in a 150 degree C environment. I
>> need to find out if a Pelitier device will cool below ambient (which I doubt).
>> If not, I think I need to put the micro into an enclosure and add cooling.
>> Shy of these, any other ideas???
>> Any leads/tips/help would be appreciated.
>Depending on the controller you are using 150C should not be real
>difficult. You won't even need high temperature solder if you don't have
>a lot of heat generated in the board. Just look for a controller that is
>fully static (eg min clock speed spec of dc). You may have to hunt for
>crystals but start with at cut in welded cans. If you need more accuracy
>than that look for sc cut crystals(expensive). Metal film resistors work
>fine. Use COG or X7R caps. Tantalum caps also work ok. BC components
>make AL electrolytics that also work fine.
More difficult than people indicate!.
Maximum silicon junction temp for reliable operation is 150C better 125C
Your semiconductors will dissipate their own power raising the junction
temperature above your 150 ambient.
If you must run at 150C then unless you go for extremely low current
operation you will have to operate with a means of lowering the
temperature and the peltier junction will not do.
Peltier is a bad insulator better to use cool water circulation or a
heat pipe to a cold surface.
Note an SC cut crystal is silly !
Unless you want a precision stability ot better than 1part per million
any standard crystal will be ok for ,1% probably 0.1% .
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