I know that slew rate specifies how fast the output voltage of an op-amp can change. But is there a measure that specifies how fast the output current of op-amps can change?

I need this information because I need to drive a capacitive load with a triangular voltage waveform. That means the the current waveform will be a square wave that swings from +Iout to -Iout.

I did a simulation with OPA541 and saw that it can it can go from +180 mA to -180 mA in 2 µs. But it's an expensive IC so I want to use a cheaper op-amp.

Here are the circuit schematic and simulation results: enter image description here

enter image description here

enter image description here

  • 1
    \$\begingroup\$ Have you considered splitting the problem into having an opamp just for voltage amplification and have a emitter follower or similar just for supplying the current? 180 mA capable opamps are few on the market. \$\endgroup\$
    – winny
    Jan 15 at 14:26
  • \$\begingroup\$ @winny You are right. But the problem is not the amount of current the op-amp can source. It's how fast it can change the output current. \$\endgroup\$ Jan 15 at 15:13
  • \$\begingroup\$ This may be summed up in the effective output inductance that some faster op-amps specify. \$\endgroup\$
    – Neil_UK
    Jan 15 at 15:25
  • \$\begingroup\$ Sure, but if you split the problem in two, you don't need to worry about the current swing capability of your opamp at all and just need to choose one with fast enough voltage slew rate. \$\endgroup\$
    – winny
    Jan 15 at 15:27
  • \$\begingroup\$ If current must change quickly, then inductance must be considered. What is the total inductance of the capacitor load, including wiring? To be sure it will be stable, it would be very useful to know the whole impedance of the load (series L, series R, capacitance) or at least have a Bode plot of Z. If you do not have data, it can be estimated by checking wiring length, type of cable, and looking at the datasheet for this "capacitor". \$\endgroup\$
    – bobflux
    Jan 15 at 16:30

1 Answer 1


If I remember well, OPA541 can go until +/- 10 A.
NB: I don't have the CS pin (current limit).

Here is an example of such behavior. Made with microcap v12.
Slew-rate of opamp is very "high".

enter image description here

And this one ...

enter image description here

Note that the product R(4)*C(2) is "important".

The "current slew-rate" \$ = ~ 1.25\$ \$A/us\$. Note SOA of the device.


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