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  1. #1
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    How stop Micro burning when GND & VCC short circuit?

    Hello friends

    if i short circuit VCC and GND Micro burn . any Micro

    VCC = 3.3V
    using LM2596 3.3V .

    LM2596 Schematic :

    Click image for larger version. 

Name:	LM2596.png 
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    how can i Protection micro from this ?

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  2. #2
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    Re: How stop Micro burning when GND & VCC short circuit?

    Hi,

    If you short circuit VCC and GND, then the supply voltage should be 0V.
    --> There is no electrical energy available.
    --> Impossible for anything to burn.

    So either your description is wrong, or there is something else in your circuit providing energy to kill the micro.

    --> please show the complete circuit, and provide a more detailed error description.

    Klaus
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  3. #3
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    Re: How stop Micro burning when GND & VCC short circuit?

    hi ,

    Yes you are right

    But it seems. The moment after disconnecting the short circuit
    The regulator burns the micro



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    Re: How stop Micro burning when GND & VCC short circuit?

    O.K. that makes more sense. Presumedly heavy overshoot during over current recovery.

    A switching regulator with soft start after overcurrent shutdown would avoid the overshoot. It's difficult to provide an effective protection with TVS diodes, a 3.3V TVS diode has typical clamping voltage > 6V. If your regulator can't guarantee safe supply voltage, you may consider a SCR crowbar.


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  5. #5
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    Re: How stop Micro burning when GND & VCC short circuit?

    Very likely a recovery overshoot. Do you have access to a digital scope?

    Solutions:
    -Either a SCR crowbar as discussed previously, which would latch and you'll have to remove the main supply to unlatch it.
    -Or replace the controller with one where a soft-start function could be implemented.
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  6. #6
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    Re: How stop Micro burning when GND & VCC short circuit?

    Or enough decoupling and maybe series choke, that the
    supply flyback can just be "soaked up"?

    You might like to put a 'scope to the power pin:gnd and
    capture a single sweep, to see what you're trying to fix.


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