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Overcurrent protection

  1. Mar 23, 2010 #1
    I need to prevent a malfunctioning load from drawing too much current from a supply of around 3Vdc@2A(max). There is already a current sensor in series with the load which outputs a voltage, Vsense, proportional to the current drawn by the load.

    I was thinking a PMOS switch with the gate tied to the output of a comparator that compares Vsense to a Vref, where Vref would represent the maximum allowed current draw for that load. When a over-current is detected the switch must shut down the load immediately and stay in that state until externally reset (by a microcontroller) or if the load resumes normal operation.

    Some kind of hysteresis (or a flip-flop??) -- or something -- is missing from this picture, and I have a feeling there exists some standard way of doing this that I'm unaware of, so any ideas are welcomed. Thanks.

    EDIT1: Oh, and btw -- high efficiency is a priority.

    EDIT2: I've already found what I need (e.g., MAX869), but if you know of a circuit with discrete components that does the same job, I'm still interested for educational purposes.
    Last edited: Mar 24, 2010
  2. jcsd
  3. Mar 24, 2010 #2


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    Science Advisor

    How about a circuit breaker or fuse?

  4. Mar 24, 2010 #3
    A circuit breaker or fuse as suggested are the simplest ways to go.

    If you're looking to go fancy you can try something similar to a crowbar circuit.
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