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crutschow

LM317 Adjustable 20V, 1.5A Supply with Simple SMPS Tracking Preregulator

LM317 supply with switching tracking prereg for good efficiency and minimal heat sink requirements.

  1. crutschow

    crutschow Well-Known Member Most Helpful Member

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    crutschow submitted a new article:

    LM317 Adjustable 20V, 1.5A Supply with Simple Tracking Preregulator - LM317 Power supply with switching tracking prereg for good efficiency and minimal heat sink reqmts.

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  2. MCU88

    MCU88 Member

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    Excellent. Now make an PCB for it an build it.
     
  3. Willen

    Willen Well-Known Member

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    Wow, Nice trick! I am using the 1st part of the circuit designed by you
    here
    , to charge my cell phone. So it's interesting to me. My cellphone takes maximum 750mA current through it and MOSFET needs medium size heatsink though.)

    I guessed heat dissipation is divided into two part (minimised too around switching area)- around MOSFET little and around LM317 chip. To save component (I think LM317 is expensive than TL431) we could totally remove the LM317, and could add a TL431 based adjustable regulator circuit as a reference voltage for LM393, couldn't we?

    After that our output part would be the the P-MOSFET. After that I cannot assume its heat dissipation though. (But I know that it would be a noisy power supply with huge ripples!)
     
    Last edited: Apr 30, 2015
  4. dave

    Dave New Member

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  5. spec

    spec Well-Known Member Most Helpful Member

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    Hi cruts,

    You do some stuff.

    The ciruit is fine as is, of course. I was just thinking: At the moment you have a buck pre reg. Have you thought about another version with s SEPIC pre reg. That way the supply volts could be anything, within reason. I only ask because it would be ideal for an application I have in mind.
     

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