Need circuit idea for programmable P.S.

Discussion in 'The Projects Forum' started by ksquare, Aug 24, 2011.

  1. ksquare

    Thread Starter New Member

    Oct 11, 2009
    I would like to build a programmable power supply that can go from 0 to 600vdc. Don't need much current, maybe 10-20ma max. Voltage increment should be 1 to 5 volts. If such a PS could be controlled by a PIC, that would be great. The trick in my mind is the PS, not the PIC part. Any ideas or suggestions?
  2. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    Well, there are three basic choices:

    Build a 600V supply and put an adjustable linear regulator past it. At 20 mA you're only burning off 12 watts there.

    Build a switcher to boost whatever convenient voltage you have to that range.

    Build a switcher followed by a programmable linear regulator. Best efficiency and still a clean output.

    Even with 1V resolution you only have 600 steps so a PIC with a 10 bit A2D could measure it, not sure if that same resolution is acceptable for a PWM control output to run a switcher. If you bang thru Microchip to the schematic for the PicKit 2 they have a step up switcher in there controlled by the PIC. It's only 13 V or so output but has the basic scheme you need to use (L1 & Q4 in 2nd page).
  3. JDT

    Well-Known Member

    Feb 12, 2009
    Use a switcher to get your 600V. There will be a resistive divider on the output that will feed back to the controller circuit to regulate the output voltage.

    This derived voltage will be compared to a reference voltage.

    Instead of using a fixed reference voltage, use a reference voltage generated by a DAC fed from a digital input.