Compaq Computer Corporation, Inc.

Bernard Nolan

Daniel Wissell

Denise McAuliffe

A short circuit protection device, which includes a comparator with a non-inverting input port, an inverting input port, and an output port, is used with first and second voltage reference signals obtained from a power supply to indicate a short-circuit condition in the power supply when the reference signals are the same. A first voltage divider is connected to the power plane of the power supply and provides the first reference signal to the non-inverting input port, and a second voltage divider is connected to the output port of the power supply and provides the second reference signal to the inverting input port, where the second reference signal is normally smaller than the first reference signal. A first time constant between the first voltage divider and the non-inverting input port provides a first time delay to the first reference signal, and a second time constant between the second voltage divider and the inverting input port provides a second time delay to the second reference signal, where the second time delay is greater than the first time delay. When a short-circuit condition occurs, the voltage levels of the reference signals become the same, changing the status signal at the comparator output port and, optionally, signaling a power-down of the power supply.

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North Falmouth, MA, United States of America

Bernard Nolan