Motorola Corporation

Other

Lloyd H Hayes

Robert Bruce Davies

Stephen P Robb

David M Susak

David F Mietus

David M Heminger

Dennis L Welty

Warren J Schultz

Judith L Sutor

John Bliss

Stephen Su

A control circuit for switching AC or DC loads and for automatically discerning the presence of an AC or a DC power supply via a switch has been provided. The control circuit is coupled to alternately render a switch operative and non-operative wherein the switch is coupled across a load which is powered up by either an AC or a DC power supply. The control circuit includes an AC/DC discernment circuit for ascertaining whether the load is powered up by an AC or a DC power supply. The control circuit also includes circuitry for comparing signals sensed by the switch with predetermined thresholds (which are a function of whether an AC or DC determination has been made) for providing logic signals to control the operation of the switch.

Load control circuit including automatic AC/DC discernment

A current source with adjustable temperature compensation in which the level of current supplied to a load is adjusted to compensate for the load's inherent change in performance with changes in temperature. The current source allows selection of the appropriate temperature compensating characteristic and operating current solely by altering internal component values.

Current source with adjustable temperature variation

A transient protection circuit provides protection from high voltage transients appearing along a transmission line by sensing a predetermined threshold of the voltage developed thereon and opening the conduction path through first and second switching circuits in the transmission line. The switching circuits are implemented with first and second serially coupled transistors sharing a common drain and enabled by a control signal during normal operation. The first and second transistors each have a diode oriented to conduct from the source to the drain for bi-directional operation. During high voltage transient conditions, a sensing circuit detect a predetermined threshold of the potential on the transmission line and disables one of the first and second transistors which opens the conduction path through the first and second switching circuits thereby suppressing the surge currents flowing therethrough.

Transient protection circuit using common drain field effect transistors

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Mesa, AZ, United States of America

Lloyd H Hayes