Current Limiting

Discussion in 'General Electronics Chat' started by cosmarchy, May 8, 2013.

  1. cosmarchy

    Thread Starter New Member

    May 8, 2013
    5
    0
    Hello all,

    Bit of a tall order but does anyone know of a high current limiting / foldback circuit which is capable of around 100A @12v?

    Thanks very much.
     
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    When arriving at 100A what is it supposed to do?
    Disconnecting the load or decreasing voltage?

    Is it PWM or continuous?
     
  3. cosmarchy

    Thread Starter New Member

    May 8, 2013
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    0
    Hi, thanks for your reply.

    It doesn't really matter if it disconnects or decreases; whatever is easiest :)

    Also, it is continuous (probability simpler than PWM I suspect??)

    Thanks
     
  4. Matter45

    New Member

    Dec 13, 2012
    26
    1
    use a shunt to get you a voltage reading, amplify it then use it to turn off some P channel mosfets in parallel lol. im sure theres a better way of doing it.
     
  5. Litch

    Member

    Jan 25, 2013
    86
    7
    Just get a circuit breaker and be done with it.
     
  6. cosmarchy

    Thread Starter New Member

    May 8, 2013
    5
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    A circuit breaker would work but it would de desirable to be able to vary the trip current
     
  7. crutschow

    Expert

    Mar 14, 2008
    13,016
    3,235
    Is it +12V?

    Could you sense the current in the ground return rather than the high side, since that can simplify the circuit?
     
  8. cosmarchy

    Thread Starter New Member

    May 8, 2013
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    Yes it is 12v :)

    Just wondered if this has been done before....got a couple of ideas on the go :$
     
  9. Matter45

    New Member

    Dec 13, 2012
    26
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    what ever you go with, care to share?
     
  10. cosmarchy

    Thread Starter New Member

    May 8, 2013
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    I don't see why not :)
    Provided it works, that is. I'd hate to share something that doesn't work.
     
  11. KrisBlueNZ

    Member

    Oct 17, 2012
    111
    14
    I would use one or more high-current N-channel MOSFETs in the high side (assuming you need to switch the high side) with a charge pump to provide the gate bias and some logic to control the MOSFETs. This circuit needs to switch the MOSFET extremely quickly otherwise it will self-destruct during switching due to high instantaneous power dissipation. This one looks good: http://www.digikey.com/product-detail/en/PSMN2R0-30YL,115/568-4679-1-ND/1993016 but you'll probably need at least two in parallel to minimise the voltage loss. You can sense the current by measuring the voltage drop across the MOSFETs after adjusting for ambient temperature. Sounds like an interesting project.
     
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