I'm planning on setting up a voltage comparator with a single rail op amp and was wondering if I still need to attach a diode to the output because it is single rail and not dual. I would think that the op amp will only produce an output when the input voltage is above the reference voltage not below it since it's a single rail. Is this correct?
Voltage comparator with single rail op amp
comparatoroperational-amplifiervoltage
Best Answer
Yes, that is correct. Usually a single supply op-amp will saturate quite near the negative rail. If the negative rail is ground, then it cannot output a voltage less than ground by itself.
Not all op-amps are suitable for use as comparators. Some, for example, effectively have diodes between the inputs. Recovery from saturation may also be rather slow.