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Power Down Identifier

IP.com Disclosure Number: IPCOM000040852D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Kurtz, JO: AUTHOR

Abstract

The power down identifier (PDI) circuit can be used to monitor power supply comparators so that if one power supply spikes or drops out for an instant, the malfunctioning supply can be readily identified after all power supplies have been shut down.

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Power Down Identifier

The power down identifier (PDI) circuit can be used to monitor power supply comparators so that if one power supply spikes or drops out for an instant, the malfunctioning supply can be readily identified after all power supplies have been shut down.

Referring to the schematic, three input wires 10, 12, 14, each connect the outputs of respective power supply monitoring comparators (not shown) to respective inverters 16, 18, 20. The inputs 10, 12, and 14 will be high until a power supply voltage goes outside its normal operating window. When this occurs, the output of OR gates 22 or 24 will go high, depending upon which comparator input went low. This in turn causes the output of OR gate 26 to also go high, clocking the four flip-flops 28, 30, 32 and 34. At this time, all data inputs to the four flip-flops will be low, except for flip-flop 34 which is tied to +5 volts and the flip-flop which is connected to the inverter which changed state first. Flip-flop 34 will then turn on LED 36, indicating that a malfunction has occurred. Also, LED 38, 40 or 42 will be lit identifying which power supply went bad. These LEDs will remain lit until the reset button 44 is pushed, thereby clearing all flip- flops.

Disclosed anonymously

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