I'm having difficulties finding information on how repeatable the output of an opamp in this simple comparator configuration is. Give the following schematic:
simulate this circuit – Schematic created using CircuitLab
I do know that a real opamp has a non zero input offset voltage, so the actual differential voltage required to make the output 0V might be a couple of mV for a jellybean opamp. So in the example above, the actual voltage might be 2.503V and might also drift with temperature, but assumed the temperature stays constant, how repeatable is it?
I'm asking, because an EE suggested using an opamp Repeatable meaning at two points in this comparator configuration (with a feedback resistor to add hysteresis) instead of a Schmitt-Trigger because 'it's more precise'. I do understandtime, that an el-cheapo Schmitt-Trigger might have a much worsehow different can the input offset voltage and gain, but in this applicationvoltages be so the actual precision (i.e. at which voltageoutput is the opamp outputs 0V) does not matter as long as it's as repeatable as possible.same?
Unfortunately, not being an EE, I cannot figure out how to read an opamp datasheet properly. How do I find out how repeatable the output an opamp really is?
Bonus question: Is the output from an opamp more repeatable than the output from a comparator or a schmitt-trigger? How can I find this out from looking at the datasheet?
PS: I've run some tests with an LM393 and a 74hc14 and with the voltage references and multimeters that I have access to, I pretty much don't see a difference. Changing the input by 10µV reliably changes the Output between 5V and 0V (at a different absolute voltage of course).
To elaborate on the purpose: The input is an analog signal with a relatively high resolution. I'm not interested in the actual value of the analog signal, but I need to know exactly when it crosses a certain threshold. The absolute value of the threshold doesn't matter as long as it stays as constant as possible.