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  1. #1
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    short circuit protectection from smps to a voltage regulator

    I want to build a variable voltage supply with LM317, which takes power from a PC smps,
    I want to utilize the short circuit protection in smps, but after regulation with LM317, the protection is not working,
    how can we implement that , after the regulation?

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    Re: short circuit protectection from smps to a voltage regulator

    before LM317 put a series pass transistor to the emitter connect a resistor for your required current so that the dtop accross becomes .7V at max current and connect base and LM317 after the resistor connect collecter to unreg+



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    Re: short circuit protectection from smps to a voltage regulator

    how can i implement that for a maximum of 10A load ?



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    Re: short circuit protectection from smps to a voltage regulator

    For 10A load it is not advisable to use a series pass transistor because the heat from the transistor will be too much.
    The maximum rating of lm317 is only 1.5 A , For a system of 1.5A the above system can be used with proper heatsink



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    Re: short circuit protectection from smps to a voltage regulator

    10A load can be implemented by parallel power transistors
    i am a bit lost with the implementation of the circuit breaker, if i can manually set the value of the current at which the circuit is breaked , then it will be more useful



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  6. #6
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    Re: short circuit protectection from smps to a voltage regulator

    it is possible pass the load current through a load resistor .1R amplify the voltage accross it using a opamp compare it with a ref voltage and trip the circuit .You can find all these features in IC LM723


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