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    Output short circuit current of operational amplifier

    Hello,

    Op-amp manufaurers specify the value of output short circuit current (Isc). In a proper design no one would connect a short to the output, what is the purpose of this value ?

    Can you please how to simulate it ? in which condition should I put my opamp like in a closed loop condiiton or open loop configuration ?

    Thank you in advance

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    Re: Output short circuit current of operational amplifier

    I'd do open loop with the opamp trying to drive to one rail.

    It tells you the upper bound on output current. For cheap/poorly specified opamps it may be the only indication of output current capability. Useful for knowing how much the opamp might draw from a supply or source into the next stage in a fault scenario.


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    Re: Output short circuit current of operational amplifier

    Read the datasheet carefully (and know how to interpret
    the way things are expressed).

    Some op amps (esp. older medium-voltage, 30V bipolar
    types) have explicit short circuit current limiting and
    as long as you respect junction temperature limits
    (or cause the temp to remain within) you can just
    short the output indefinitely and measure. Such
    parts ought to have a min (for drive) and max (for
    reliability) limit-pair.

    Other op amps may spec output short circuit current
    as a -minimum- value to be provided, but have no
    limit to the maximum other than the output devices'
    on-resistance (or, for current-mirror outputs, the
    internal bias setpoint). These may or may not be
    guaranteed to survive long term short circuit /
    overcurrent operation.

    Maybe pull output I-V curves on an expendable
    test sample, and do it twice to see if you drifted
    anything.


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    Re: Output short circuit current of operational amplifier

    Dear Friends,

    I read some usefull application of knowing Isc, for example in case of driving high CL, some of the solution is connect small Rs inseries, with the help of the Isc then we can calcultae Rs = Vo(peak)/Isc.

    I will connect a short circuit to my op-amp in unity gain configuration and I will post the result here to further discuss it

    Thank you once again



  5. #5
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    Re: Output short circuit current of operational amplifier

    Dear Freebird

    kindly see below the short cicrcuit current test for my fully differential amplifier, the maximum current at the output is about 28 mA.

    I have shorted the putput load and swet the input voltage to get the plot

    Click image for larger version. 

Name:	ISC.PNG 
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ID:	156092

    Regards



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