Circuit and method for detecting the state of a switch with reduced power

A circuit and method are disclosed for detecting activation of a switch, such as a mechanical switch, having a first terminal coupled to two or more voltage sources, with each voltage source providing a distinct voltage level representing a logic high level. The circuit includes first circuitry, hav...

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Bibliographic Details
Main Author YOUSSEF TOM
Format Patent
LanguageEnglish
Published 21.06.2005
Edition7
Subjects
BASIC ELECTRIC ELEMENTS
ELECTRIC SWITCHES
ELECTRICITY
EMERGENCY PROTECTIVE DEVICES
RELAYS
SELECTORS
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Summary:A circuit and method are disclosed for detecting activation of a switch, such as a mechanical switch, having a first terminal coupled to two or more voltage sources, with each voltage source providing a distinct voltage level representing a logic high level. The circuit includes first circuitry, having an output coupled to the switch for initially placing a first voltage across the switch representative of a logic low level. The circuit further includes second circuitry having an input coupled to the switch for sensing a voltage differential appearing across the switch and an output for indicating whether the voltage appearing across the switch is at any voltage representative of the logic high level, the second circuitry being controlled to selectively eliminate static current drawn by the circuit based upon the value of the output of the second circuitry.
Bibliography:Application Number: US20020147639