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Current limit for 5V @ 120mA

Discussion in 'General Electronics Discussion' started by Allenlsk, Jul 26, 2017.

  1. Allenlsk

    Allenlsk

    1
    0
    Jul 26, 2017
    Hi,

    I am working on something that can limit the current draw from a 5V source with current of 500mA. But I wanted to limit the current draw to only 120mA.

    May i know how should I do that, or is there a standard IC that can do it, I try to search for current limit IC but can not find one that is giving 5V @ 120 mA

    Please help
     
  2. Minder

    Minder

    2,852
    593
    Apr 24, 2015
    LM317 can be used as a current regulator, there should be alot of examples out there.
    M.
     
  3. BobK

    BobK

    7,626
    1,654
    Jan 5, 2010
    Please explain further what you are trying to do. If you intend to hook up a device that requires 120mA at 5V, you can connect it directly to a 5v, 500mA supply. It will use only the current it needs.

    The rule for power supplies is that they must provide the correct voltage and at least the required current. In fact, you should normally allow a margin for the current, never run a power supply at the maximum current, or it will likely fail early.

    If, on the other hand, what you want is something will set the voltage to whatever it takes to push 120mA into the load, you need a constant current source, as Minder said.


    Bob
     
    davenn likes this.
  4. Audioguru

    Audioguru

    2,583
    585
    Sep 24, 2016
    For an LM317 to produce an output limited to 120mA at +5V then its input must be at least +6.75V.
     
  5. davenn

    davenn Moderator

    13,289
    1,756
    Sep 5, 2009
    what Bob said ......

     
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