Joining multiple voltage regulators or PWM ?

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killertoffy
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Posted by killertoffy: Wed. Jul 25, 2007 - 05:08 PM
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Again, I need your ideas and experience ;-)

I want use a peltier to cool down a ccd, controlled by a mcu with a temperature sensor.
It is rated 6A and 15.4V...

Well now I need a power supply for that thing...

I wondered if I can start with 20v then use voltage regulators to bring it down to around 15V.

Since I know no regulator that can output 6A at 15.4V, is it imaginable to "join" multiple regulators to produce 6A ?

Or is better to design a real switching power supply, maybe by pwm on a 20V source ?
(which would allow me to control the peltier which is nicer than on/off)

Knowing that efficiency doesn't matter, and as usual the simpler the better ;-)

Thanks for you time ;-)

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Learning and Information, General Electronics
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Plons
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Posted by Plons: Wed. Jul 25, 2007 - 07:44 PM
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Parallelling (what a word .. ) of analog regulators is possible. If you go through the datasheets of f.i. the LM317, you'll find an example.

Whether or not it's wise ..... 5V @ 6A makes 30 Watt.
I think that a switching regulator is the way to go.

Nard

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ossi
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Posted by ossi: Wed. Jul 25, 2007 - 08:50 PM
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If you supply the peltier with 15 Volts and 6 Amps
the peltier will deliver 15*6=90 Watts from its own
power plus the heat it removes from the CCD. So
you have to bring away at least 90 Watts with a
good heatsink.

In this case I would not care about 30 additional
Watts from a few LM317s.

Think big here. Use a very very large heatsink and
very good fan-cooling.

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killertoffy
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Posted by killertoffy: Wed. Jul 25, 2007 - 10:16 PM
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You're making a point there...
I should probably start with 12V from a PC power supply.
If then I can get rid of the heat with the limited weight and space I have, I'll go to 15V.

Maybe I can improvise a meat grill while taking exposures ;-)

Thanks for your lights !

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