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OPA548: Current limit resistor Rcl power rating

Robin van Schaijk
Prodigy 10 points
Part Number: OPA548
Other Parts Discussed in Thread: OPA541

Hello,

I am working on a design using the OPA548. The current limit should be around 1.5A, so I selected a 33kR resistor.

On the first page of the datasheet it is stated that a 1/4W resistor should be used for this, I was wondering why this is required.

The output current of the ILIM pin is limited by the 13750R internal resistor. So when I apply a 33kR resistor, the power dissipation in this resistor will only be ~330uW.

Could you please explain why this 1/4W resistor is required?

  • +1
    Guru 140200 points

    Hi Robin,

    other Power OPAmps like the OPA541 e.g. perform the current limiting with a resistor which has to withstand several Watts. The picture on the front page of datasheet of OPA548 and the shown 1/4W resistor there is only to inform you that the current limiting circuit of OPA548 works differently and only needs a very tiny programming resistor.

    Kai