What happens when the output voltage of an op-amp (say in a voltage follower/inverting configuration) should be higher than a certain amount (say 10V) and on the output I place a 5V zener diode in reverse, followed by GND?
simulate this circuit – Schematic created using CircuitLab
On the one side, it should be Vin, right? But I think it must also be less or equal than 5V because of the Diode
Best Answer
If the inverting input is low, the op amp it will try raising the output voltage, so via the feedback it will try to match the +15V from the noninverting. As hard as possible. However, at the same time the zener sinks as hard as possible. In the end you get the equivalent of a short circuit and either the opamp, or the zener, will eventually become very hot and might get destroyed.
Realistically, the TL081 is short-circuit protected and the output current capability is not incredibly high, so both parts will just get hot and the output voltage will be somewhere in-between 5 and 15 volts, probably close to 5, because, as said, the current capability is not incredibly high.