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OPA171-Q1: Fixed reference switches with respect to the Input frequency

Part Number: OPA171-Q1
Other Parts Discussed in Thread: OPA171, OPA2990


I am using OPA171 op-amp for simple comparator operation.


Op-amp supply: +12V and -12V

Non-inverting terminal: 2.5V fixed reference (by voltage divider)

Inverting terminal: PWM input with 1KHz (0-5V)

Expected Output: Switched Output with +12V/-12V with 1Khz frequency (wrt to input PWM)

Issue:  Non-inverting fixed reference is switching with respect to the input PWM frequency (0-2.5V). it seems to be abnormal to me. Experts please clarify if it is normal and why.

I have attached the circuit below. Please let me know if you need any additional information.