I mapped out a fan controller circuit that uses an LM393 comparator, and I'm trying to calculate what it's doing.
If I used basic ideal rules, a certain transistor would not be on at all due to the infinite input impedance of the LM393. (it's emitter resistor terminates at the inv. input, until the LM393 output goes low creating a 2nd path)
When I simulate it with circuit wizard, they say about 4uA @4V, 6uA @6V into the inputs.
For op-amps in general, where in the datasheet can find or figure out the current into them, with any confidence ? I see nanoAmps
Whats a rule of thumb ?