Op Amp Reverse-polarity Protection

Sometimes when carelessly hooking up the DC supply voltage to an op amp, you may reverse the polarity of the voltages. Doing so, however, cause result in a zapped op amp IC.

If you feed positive voltage into the negative supply terminal, -Vs, this can potentially destroy the op amp.

The way to counter this if you happen to make this mistake is to place a diode between the negative supply terminal and the negative voltage. This is shown below:

When you connect a diode in this fashion, if positive voltage is placed on this negative supply terminal, current will not flow, because the diode is reverse-biased. This protects potentially fatal voltage from carrying out its effect if voltage polarities are reversed.