Voltage Regulator Protection (EE Tip #104) | Circuit Cellar | HYPES  - Electronic components | Scoop.it
In many cases, the load connected to a voltage regulator is not returned to ground. It goes to an even lower voltage or perhaps even the negative power supply voltage. Op-amps and level-shifters come to mind. In such cases, a diode (1N4001 or equivalent) connected across the output of the regulator IC usually provides sufficient protection.