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Browse Prior Art Database

Auto-Programmable Over-Current Power Supply Detection Circuit

IP.com Disclosure Number: IPCOM000039908D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Riggio, SR: AUTHOR [+2]

Abstract

A technique is described whereby an electronic sense circuit provides detection of output current amperage which exceeds the allowable load- operating range of a power supply. This detection is accomplished without momentarily driving the output current to its catastrophic limit before a shut-down occurs. The concept is unique in that it is automatically programmable to take into account variations in loads, that can occur when computer configurations change, as in the addition of feature cards to increase the function of the computer. In prior art, over-current protection of power supplies was accomplished by using a hysteresis or threshold comparator circuit. The trip point was usually set slightly above the maximum operating current value.

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Auto-Programmable Over-Current Power Supply Detection Circuit

A technique is described whereby an electronic sense circuit provides detection of output current amperage which exceeds the allowable load- operating range of a power supply. This detection is accomplished without momentarily driving the output current to its catastrophic limit before a shut-down occurs. The concept is unique in that it is automatically programmable to take into account variations in loads, that can occur when computer configurations change, as in the addition of feature cards to increase the function of the computer. In prior art, over-current protection of power supplies was accomplished by using a hysteresis or threshold comparator circuit. The trip point was usually set slightly above the maximum operating current value. With the advent of customer configurable computers, the load current range of each output voltage varies from system to system. As a result, the maximum over-current trip-point detection circuitry is no longer adequate. The technique, described herein, provides an auto- programmable over-current detection circuit which essentially reads the value of the steady-state load current established at start-up time and then stores this value in a resistor/capacitor (R/C) network. The over-current trip point is then set as a percentage of the nominal operating output current, regardless of the configuration of the system. In the actual operation of the auto-programmable over-current detection circuit, resistor 10 and capacitor 11, as shown in the figure, are used as the network that stores the value of the steady- state load current at star...