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OPA541: resistor recommendation

David Park
Expert 7240 points

Part Number: OPA541

Hi,

Customer would like to design as below configuration.

operating condition is +/-25V, 15A and gain is 4~5.

Please recommend proper resistor value instead of 0.1Ohm

image.png

Thanks.

  • 0
    TI__Genius 17566 points

    Hey David, 

    Happy Holidays!

    .1ohm is traditionally a bit on the lower side for ballast resistors, though it is certainly a functional size for running parallel amplifiers like this. When we have a relatively low value ballast resistor like this, layout becomes even more important, especially in ensuring that the output traces are run in a symmetrical manner. 

    What makes you ask for a value other than .1Ohm? I have seen customers successfully implement with low value resistors like this before. As mentioned before, the lower value does add the requirement for more care, though there is often little choice in sizing the ballast to be much larger when we are talking about many amps of current flowing through. 

    Here is a nice app note on the topic of paralleling power amps together: Paralleling the OPA593 High-Voltage, High-Current Op Amp for 2 × Output Current

    Can you tell me a bit about this application? 

    Thanks,

    Jacob