I'm looking for a method of protecting a circuit from overvoltage (perhaps by turning off a FET in the presence of higher voltages). The input voltage is normally +5v, but if plugged into the wrong system it approaches 30 volts which destroys the downstream circuitry. I'm trying to find a way to isolate the overvoltage without shorting the input (so a simple fuse or TVS is out), but have been unsuccessful so far. My original plan was to use a comparator to switch a MOSFET off when a pre-determined threshold is exceeded, but I'm unable to come up with a proper driver for the FET gate. Any suggestions would be greatly appreciated!