Measuring Slew Rate of an op-amp

I am trying to measure Slew Rate of the BA4580Rxxx op-amp. I want to apply a pulse using Max038 waveform generator IC to the input of the op-amp. Then, read the output of the op-amp with an ADC. While the amplitude of the pulse and the frequency at which the Micro-controller is working are known, I could have a counter and calculate the time interval between the output amplitude reaching 10 percent and 90 percent of the applied input pulse. Now some questions appear:

1. What should be the rise time of the applied pulse in the input?
2. What should the amplitude of the pulse be?
• @V.V.T, Thank you, but It doesn't talk about the rise time of input pulse. Commented Dec 18, 2023 at 8:23

• The slew rate of an opamp must be measured with (strong) feedback applied.

• The rise time of the input step should be as small as possible (much smaller than the expected slew rate).

• The amplitude of the input step must be large enough to bring the input stage into saturation for a short time (until the feedback brings the whole crcuit back to linear operation), but low enough not to bring the output stage into saturation.

• Under these conditions, the slew is identical to the slopes of the output signal (it is NOT the time between the 10%.....90% points)

• Well I am trying to measure some parameters of the op-amp IC. How would I know if the amplitude of the pulse applied brings the first stage into saturation but not the second? I don't have access to the inside circuit of IC. Commented Dec 19, 2023 at 4:59
• I did not speak about the 2nd stage. It is sufficient to overdrive the 1st stage with 10...50mV.
– LvW
Commented Dec 19, 2023 at 7:49