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OPA541: Not using a current limit function

Part Number: OPA541

Hello, Expert,

I would like to double check whether my understanding is correct.

If we decided not to program a current limiting function with RCL (say RCL = 0 Ohm), does this mean that the device will be just internally current limited to 10A? Although if we substitute RCL = 0 to Eq (1), we get ILIM = 0.809/0.057 = 14.59 A, we think that internally the output will be limited.

Please let us know your thoughts.

Best Regards,
Masaru Oinaga

  • Hi Masaru, 

    does this mean that the device will be just internally current limited to 10A?

    The 10Apk is the approx. current limit figures when operating at room temperature, if RCL = 0 ohm. There are approx. -/+ 10% margin on the current limit.  In the real world setup, the RCL will not be 0. At 10Apk, RCL = 24mOh approx. The PCB traces at the output will not be 0 ohm. 

    There are other operational conditions that affect the current limits.  The die temperature is one. If the die's junction temperature is elevated, then the BJT's output current will be also limited (~ -2mV/C across the base and emitter).  

    The OPA541's internal current limit would be guided by the SOA curve for the proper operation. The OPA541 may get damaged if it is operating outside of SOA curves. So OPA541 is likely unable to delivery 14.6Apk from the equation above the room temperature. 

    (if the part is cooled to lower temperature, say -40C, the theoretical output peak current may be observed).  

    If you have additional questions, please let me know.