I am using opa2350 as a current sensor in inverter as that combination:
and sometimes, when output voltage is >20 VAC i have problem with sensing current in negative sinusoidal:
Positive half looks quite okay. I try it with diffrent shunt resistor value, but the problem stay always for negative voltage.
Since you power OPA2350 from 3.3V single supply, +/-20V can only be applied on the input and then attenuated to be within 3.3V supply. For that reason, you must swap the resistors to attenuate the input signal by 20 instead of amplifying it as your circuit does right now - see below.
Alright, it doesn't matter I fix it with my software. But now I have another question. I uesd tto probe my current feedback at the output of OPA2350, but now I se something like this (pink channel):
The input common-mode and differential input capacitance (2.5pF and 6.5pF, respectively), together with the input resistor, form a zero in the close-loop transfer function resulting in a phase shift that may lead to instability if the zero occurs within the bandwidth of the part. For that reason, you should add roughly 0.5pF cap across the 20k feedback resistor to cancel the zero - see below. For more information on this topic, please review stability section of TI precision labs training video under following link: https://training.ti.com/ti-precision-labs-op-amps
