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Op-amp max current output vs frequency
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ricko_uk:
Hi,
does op-amp current vary depending on frequency? I'm thinking most likely the max current output decreasing as frequency increases perhaps, due to losses and parassitics? I googled it and looked on few datasheets but could not find any such graph/parameter.

Thanks
profdc9:
What you want to look at is slew rate.  Slew rate is the maximum change to the output of the op-amp in volts/second.  So for example, if the op-amp is driving a 100 ohm load, and the slew rate is 5 volts/microsecond, then the change in current is 50 mA/microsecond.  So for example, for an output at 1 MHz/(2 pi) or about 159 kHz, the maximum oscillation amplitude in current is going to be 50 mA.
magic:
There is a current slew rate too. If nothing else, the slew rate times output stage transconductance is the limit ;) and it may be worse due to input capacitance of the output transistors and limited drive current available from the gain stage.

But if it's not specified then it probably is not a problem in any reasonable application and the usual voltage slew rate is the limit, as outlined above. Unreasonable applications where this may not apply involve: driving very high current at very high frequency into very low impedance load.
Vovk_Z:

--- Quote from: ricko_uk on January 22, 2020, 03:27:27 am ---does op-amp current vary depending on frequency? I'm thinking most likely the max current output decreasing as frequency increases perhaps,
--- End quote ---
Max output voltage usually will decrease with frequency, but current not so much. Actually we can think that it doesn't change.
David Hess:
It would be interesting to test.  Output current slew rate will be primary limited by voltage slew rate into the output load.  Voltage slew rate is limited by the compensation.  Current gain of the output transistors drops with frequency however that is way beyond the other limits.
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