-15 vdc 3amps output from -55vdc

Discussion in 'General Electronics Chat' started by Roque, Sep 16, 2014.

  1. Roque

    Thread Starter Member

    Sep 16, 2014
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    Hi guys i am a newbie here..was wondering if someone could please advise me how to get -15v dc 3amps...from an input of -55v dc thanks.
     
  2. #12

    Expert

    Nov 30, 2010
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    Probably a fast switching buck converter, but I can't get the Texas Instruments Simple Switcher website to work with negative voltages right now.
    You need to specify the range of the voltage supply, like -52 to -56 volts to get a proper design, and the range of the load. Is it always 3.00 amps? Probably not. What about allowable output voltage? -14.8 to -15.2?

    I've been sick lately, but this is a start. Tell us some more numbers and you'll probably get a good answer soon.
     
  3. ScottWang

    Moderator

    Aug 23, 2012
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    Where is the -55Vdc came from?
     
  4. #12

    Expert

    Nov 30, 2010
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    Pretty much what I said. How stable is the -55 volt supply? Loads down to -50 volts when you use up 3 amps? Has noise on it from the generator? Lots to consider if you want something reliable.
     
  5. Roque

    Thread Starter Member

    Sep 16, 2014
    68
    2

    The voltages at the torroid is 35v ac..after rectifying it jumps to 54v to be specific...tried the lm2576...getting +15 v ..which is good...need -15 v dont know how to work that..using a lm2576..i tried and busted one ic.
     
  6. #12

    Expert

    Nov 30, 2010
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    (Theoretically, 35 VRMS rectifies to less than 50 volts.) Did you make a rectifier for the negative voltage or do you need an inverting design to get -15VDC from +54VDC?

    There is a way to do an inverting buck regulator with an LM2576, but it isn't the right voltage range. Need to keep searching.
     
    Last edited: Sep 17, 2014
  7. Roque

    Thread Starter Member

    Sep 16, 2014
    68
    2

    yes have made a rectifier ,its got +55v dc and -55vdc have used the positive rail to get +15v which works great using the lm2576hv ,but -15v is driving me nuts ....lol...well to give you an overall idea of the power supply ...it all started of with a audio 18 channel mixer ,which had a faulty smps, cant get hold of a similar smps ,so decided to make my own basic power supply ,being a 18 ch mixer i am guessing would need approx 3 amps..well thats the story .
     
  8. #12

    Expert

    Nov 30, 2010
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    34 minutes of searching and no joy. Chips labeled 3 amps won't do 3 amps when inverting from +15V to -15V. 60 volt chips are not numerous.
    At this rate of progress, you might end up adding a 15VAC transformer to get a lower working voltage so you can find a regulator that will work for you.

    ps, I don't think you need 3 amps for an audio mixer. Those things have outputs in the milliwatt range.

    If you could get a -15V switcher, what would you feed it? 120 VAC?
     
  9. #12

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  10. Roque

    Thread Starter Member

    Sep 16, 2014
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  11. Roque

    Thread Starter Member

    Sep 16, 2014
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    would feed it 220v ac..
     
  12. #12

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    Nov 30, 2010
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