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OPA564-Q1: The output current limit of OPA564

user5792198
Prodigy 20 points
Part Number: OPA564-Q1

1, Reference opa564-q1 datasheet page15, I set the Rset=47K; so, the Ilim=0.4615A.

2, you can see the follow image, CH1:output signal, ch2:IFLAG, CH4: output current;

  Current Limit Flag high, when the output current is about 210ma，

 

3,Question: Is there such a big difference between the measured current value and the theoretical value?

  • 0
    TI__Guru* 93105 points

    Hello user5792198,

    The OPA564-Q1 current limit accuracy should be close to what the equation produces. The datasheet graphs 31 and 32, OUTPUT CURRENT LIMIT vs RSET provide an approximation of the typical current limit performances. I would not expect it to be off by the large amount you are seeing.

    I don't know Chinese characters so I am unable to interpret the DSO information associated with Channel 4. Is the 212 mA a peak current, RMS current, or other? Can you provide your OPA564-Q1 circuit diagram and all external input/output information so that I can better understand how it is being applied? I need to see how the Channel 4 current is being measured. Are you using a current probe? Is the Channel 4 ground reference at the same point as the #4 tab on the left side of the DSO screen?

    Regards, Thomas

    Precision Amplifiers Applications Engineering

  • 0 in reply to Thomas Kuehl
    TI__Guru* 93105 points

    Hello user5792198,

    Do you have anymore information for us? If you have resolved this on your own, please let us know by closing this e2e inquiry.

    Thomas

    Precision Amplifiers Applications Engineering

  • 0 in reply to Thomas Kuehl
    Prodigy 20 points

    hi,

          1,The problem ahead is that there is something wrong with my test method.

          2,  Current Limit Flag high, when the output current is about 448ma. 

  • 0 in reply to user5792198
    TI__Guru* 93105 points

    Hi,

    Do you still require our assistance? If you would like to go off and try to resolve the measurement issue it would be helpful to us if this e2e inquiry could be closed for now. If you find something you don't understand a new e2e could be opened.

    Thanks, Thomas

    Precision Amplifiers Applications Engineering