I made an electronic load using 4 irl540n and lm358 opamp, schematic is as in the picture, on the input i placed an rc filter, that should filter frequencies above 200hz, the pwm frequency from the uc is around 900hz, but the output of the rc filter that's connected to input of the opamp isn't clean, it has a sawtooth shape and it's peaks reach around 800mV, any idea why's that and another problem that it's too sensitive, if i set 0.5% duty cycle the voltage on the gate of the mosfets already reaches 2v, how can i lower the gain of the opamp? by changing values of R15 and R18?
Would really appreciate some help
Would really appreciate some help