The SMH4811A is designed to control hot swapping of plug-in cards operating from a single supply ranging from 20V to 500V. It provides under-voltage and over-voltage monitoring of the host power supply, drives an external power MOSFET switch that connects the supply to the load, and also protects against over-current conditions that might disrupt the host supply. When the input and output voltages to its controls are within specification, it provides a Power Good logic output that may be used to turn loads on (e.g., an isolated-output DC-DC converter, or drive a LED status light). Additional features of the SMH4811A include: temperature sense or master enable input, 2.5V and 5V reference outputs for expanding monitor functions, two Pin-Detect enable inputs for fault protection, and duty-cycle over-current protection.