Cherry Semiconductor Corporation

Texas Instruments Corporation

James Alvernaz

Robert H Fugere

Kevin J Dropps

Herbert A Thompson

A hysteresis generator for providing a comparator with a precision hysteresis reference input. An output of the comparator controls a switch which determines whether or not a reference current is applied to a resistor. The resistor is connected between a reference voltage and an input to the comparator. A buffer amplifier provides the reference voltage to the resistor. The reference current is taken from a second resistor connected between the output of the buffer amplifier and the input of a current mirror. The current mirror applies its output current to the first resistor. A diode may be inserted between the output of the buffer amplifier and the first resistor to make the hysteresis voltage generated by the current applied to the first resistor substantially temperature independent.

Precision hysteresis generator

A negative input voltage comparator that compares a negative input voltage signal against a positive voltage signal in a circuit, such as an integrated circuit. The negative input voltage signal is effectively isolated from the circuit by means of a series resistor in the base-emitter circuit of a transistor which is connected in the output leg of a current comparator.

Negative input voltage comparator

A solid state starting system for electric motors having main and auxiliary windings of the capacitor start induction run and capacitor start-capacitor run types uses a triac serially connected to the auxiliary winding. The system differentially measures the auxiliary winding voltage and provides a triac gate signal when in the START mode. When the auxiliary voltage reaches a calibratable cut-out voltage the triac is disabled until the auxiliary winding voltage decreases to a level below a calibratable cut-in voltage. The slope of the percent motor speed cut-out versus percent line voltage is calibratable to permit compensation for variations in line voltage. The triac can be directly driven or driven through an optically coupled interface having a triac output (OCI).

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West Greenwich, RI, United States of America

James Alvernaz