PIC controlled power supply

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DRCT
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PIC controlled power supply

Post by DRCT » Thu Nov 03, 2005 10:28 am

Anyone have a schematic for a PIC controlled power supply? I would like to build a power supply that could output a 0-20v, 0-10A and be varied via a PIC such as having the PIC output a 0-5v signal to vary the 0-20v P.S. output.
Any help appreciated!

<small>[ November 03, 2005, 10:30 AM: Message edited by: DRCT ]</small>

bodgy
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Re: PIC controlled power supply

Post by bodgy » Sat Nov 05, 2005 5:49 pm

If you can get hold of a 2002 copy of Elektor electronics they had a Pic controlled power supply project.


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haklesup
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Re: PIC controlled power supply

Post by haklesup » Mon Nov 07, 2005 12:10 pm

I don't have a schematic but if I were to do this I would start with any variable PS with a potentiometer adjustment and then replace that with a digital pot like these from Maxim and drive that with the PIC. Add complexity by doing the same to the current limit and/or add a display.

If the PIC you choose has a D/A analog output, you can use that to drive a voltage reference instead of a digital pot. Naturally you need a PS circuit that adjusts using a low current refence voltage (tracking).You might be able to apply this to a LM317 type adjustable PS IC and drive the Adj pin directly.

(A schematic for a PIC circuit is incomplete without the PIC code anyway)

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philba
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Re: PIC controlled power supply

Post by philba » Mon Nov 07, 2005 3:12 pm

I don't believe there are PICs with DACs. However, you can use PWM to generate a variable voltage output. A low pass filter which has a very low F3db (10s of Hz) can eliminate the vast majority of the PWM induced ripple. You would want to use the highest possible PWM frequency as well.

It can be made to work suprisingly well for low frequency signals.

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