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Looking for switching supply with 110V AC in and about 400V DC out

  1. Jul 30, 2012 #1
    As the tittle, I am looking for off line switching supply of about 400VDC output. Anyone know who make this?


  2. jcsd
  3. Jul 30, 2012 #2


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  4. Jul 30, 2012 #3
    Thanks for the reply, I am look for a small power supply, something like 200mA 400V output only.
  5. Jul 30, 2012 #4


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    Does it have to be isolated from the mains?

    American computer power supplies have a voltage doubler input which produces about 350 volts across a large capacitor.
    This then powers an oscillator which is transformed to lower voltages.

    However, you could tap off the 350 volts if your application allowed you to do this safely.
  6. Jul 30, 2012 #5
    Thanks for the reply. I need it to be isolated. Looks like I am going to have to learn how to design switching power supply!!!:cry::bugeye: I so wish I had stop and talk to my engineer those days. I just let him did all the high voltage supply designs. The electronics part is quite easy, it's the transformer, I just never design transformers before.

    The only one I found is the Alcopian 400V unregulated supply. It's too big and too expensive. I just want a 200mA ACAP( as cheap as possible).

    They just don't have anything over 48V!!! Then it jump to 1KV+!!!
  7. Jul 31, 2012 #6
  8. Jul 31, 2012 #7
  9. Jul 31, 2012 #8
    My bad - I just went by their little check box that said "isolated". I guess I could have looked at the doc.

    On Semi has one they are marketing as isolated as well. This may be worth looking at as well...

  10. Jul 31, 2012 #9
  11. Jul 31, 2012 #10


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    Not sure if you prefer to make or buy.

    To Buy:


    About $7K

    To Make:

    At the 80W range the typical solution is to use a PFC boost fed from the line to get a large intermediate voltage, like 500V. Then drop that down with an isolated flyback.

    These data sheets give you most of what you need to design the application circuit.

    http://cds.linear.com/docs/Datasheet/3748fa.pdf [Broken]
    Last edited by a moderator: May 6, 2017
  12. Jul 31, 2012 #11

    I see the LT is an isolated design. I'll read up on this. Thanks for your info. I want to make it under $100!!! Yes I am cheap....very cheap!!!

    Last edited by a moderator: May 6, 2017
  13. Jul 31, 2012 #12

    jim hardy

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    400V 200ma ,, only 80 watts?

    is there enough room in a PC 200 watt supply to remove one or more of the high current 5volt windings from the donut and replace them with 400 volt windings of tiny wire?
    Or disconnect one and use it to energize another donut with your hv windings?
    Obviously you'd not pick the one that's used for regulation feedback.

    Seems to me you get a volt or two per turn on those things

    Tedious, but you cant beat that for cheap.

    you'll need fast high voltage rectifiers...... i am not fluent in those.
  14. Jul 31, 2012 #13
    You read my mind. My problem actually is on designing the transformer. I never once in my life design a transformer. I talked a lot with my former engineer that design all the HV switchers, he talked a lot on the core material, maximum volts per turn. Problem we had a fall out!!!

    Rectifier is not too bad, I did involved in all phase of the switcher design on and off except the transformer. I am thinking about getting a LV off line supply like you suggested, get one I can find the schematic and do it.
  15. Aug 1, 2012 #14


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    Do you need a fast transient response and/or efficiency? If not I know how I would do it for cheap.

    Get a 1:1 isolating transformer from digikey.

    Follow it with a rectifying quad multiplier. Like this:

    With 110Vac you should get a lousy 600Vdc if you size the caps right.

    Use a high voltage heat sinked FET (maybe put a high power resistor in series with the FET to share some power) and a high voltage zener plus resistor to make a lousy LDO to ~415V. Since you are just building one you can trim it with a pot. The trick will be to survive the turn on transient but this should be easy with a well placed feed forward cap.

    Use a floating LM371T to drop out the remaining 15V and get the 400V output. This stage can also be trimmed with a pot.

    I am sure this would come in under $100 and it would be super easy to solder together in an afternoon. Much easier to debug than a SMPS too.
  16. Aug 4, 2012 #15

    jim hardy

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    among the debirs on my hard drive was an appnote for this TI IC

    UCC28517 EVM

    document number is SLUU117C − September 2002 − Revised July 2003

    has partslist including the inductor and pcb layout
  17. Aug 4, 2012 #16
    Thanks, this helps. I have to study that a little first. I am looking at different option. I am debating on using switcher for my guitar amp design as a lot of rocker are at my age or older, nobody want to carry a heavy amp!!!! There are company like Crate that came out with amp using switchers, but they had reliability issue.
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