Stable supply-side reference over extended voltage range with hot-plugging compatibility

In one embodiment, the operating range of an over-current detection circuit is extended to higher input voltage levels by providing a reference-voltage generation circuit for the detection circuit with voltage protection circuitry that applies an additional voltage drop to shield other vulnerable transistor devices from the higher input voltages. In addition, bypass circuitry is provided that is inactive at the highest input voltage levels, but actively bypasses at least some of the voltage protection circuitry at relatively low input voltage levels to apply a voltage drop that is sufficient to ensure proper operation of the vulnerable transistor devices at the low voltage levels. In one implementation, the vulnerable transistor devices are NFET devices in a programmable current mirror of the reference-voltage generation circuit. In addition, a stiffened voltage divider helps to ensure sufficient voltage drop at the low voltage levels. The protection and bypass circuitry also enable hot-socketing operations.