App note: External current limiting circuit

Posted on Saturday, May 5th, 2012 in app notes by DP

Learn how to implement fixed current limiting in power-supply designs:

In every power supply application there exists the possibility to short the output to ground causing excessive current to be drawn from the power supply. In order to limit the output current from becoming excessive the following examples of current limiting circuits are suggested.

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2 Responses to “App note: External current limiting circuit”

  1. Michael Taylor says:

    I would note that the techniques described only limit current to the maximum allowed current limit rather than reduce the current at the pass transistor (top left in above diagram) in the case of a fault condition. So I wouldn’t recommend it for moderate to high current applications (say above 3 to 5A).

    EDN Design Idea Circuit adds current-foldback protection (EDN July 21, 2005) outlines a common current fold-back design, used to reduce the current in the case of excess current draw, as often associated with component or circuit failure, e.g. a short-circuit in the power supply’s load.

    Thanks for the great blog.

  2. hernan says:

    my input 12v 500ma, I want at the output 12v 400ma….how to??

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