Below is my Circuit and Voltage Waveforms for the Comparator Circuit. My question is -- In the Highlighted area in the waveform - why is the V(CMP_OUT) not high since inp_u2 (blue) is higher than inp_u1(green) for this interval?

My goal is that CMP_OUT should be high whenever inp_u2 is higher voltage than inp_u1.

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  • \$\begingroup\$ Your other question looks similarly rushed. Do take time to read the datasheets, instead of jumping to SE to ask a question that will, most likely, need hours to get an answer. It will only help you in the long run. \$\endgroup\$ – a concerned citizen Jan 8 '19 at 13:59
  • \$\begingroup\$ @aconcernedcitizen Thank you for your feedback. I agree and I will try and improve. \$\endgroup\$ – Neil Dey Jan 10 '19 at 0:37

The OA does not work if the input is at V-. There are limits to the common mode range.

This old part does not work to V- or Vee or below ground as some do. Therefore connect -V = -0.5 or more.

Or keep Vin+/- >0.5V < Vcc-2

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  • \$\begingroup\$ I get the same result when I connect the Vcc- to -12V: imgur.com/a/ZPUfbQL \$\endgroup\$ – Neil Dey Jan 8 '19 at 23:35
  • \$\begingroup\$ You do not show the Vcm. Is that assumed to be floating? Vcm= avg(in1,in2) w.r.t. 0V \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jan 8 '19 at 23:36

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