International Rectifier Corporation

John E Parry

Thomas J Ribarich

Toshio Takahashi

Ajit Dubhashi

David C Tam

Ray J King

John J Ribarich

Christopher C Chey

Jonathan Adams

Aristide Tchamdsou

A Class D amplifier system utilizing high voltage level shifting technology and an adaptive power supply which adjusts the magnitude of the output voltage based on audio input levels to reduce switching losses at low audio input levels. The amplifier system of the present invention also removes any DC offset at the output by providing an equal positive and negative power supply with respect to ground.

Class D high voltage amplifier system with adaptive power supply

A circuit for recovering a signal of interest which is offset by a common mode displacement, such is the case when the signal is the voltage across a current sense resistor located on the high side bus or between the switches of a motor controller circuit. The circuit of the present invention converts the voltage across the resistor into a pulse code modulated data, then downshifts the voltage, and then recovers the signal of interest at the lower voltage by demodulating the signal. The recovered signal is then processed, either with a synchronized sample and hold circuit to provide an analog output, or with a counter and latch to provide a digital output.

Linear current sensing circuit for motor controller

A model and computer program for designing the output stage of a high frequency electronic ballast for a fluorescent lamp. The user specifies a plurality of parameters relating to the operation of the fluorescent lamp, including lamp running power, running voltage, maximum preheating voltage for the lamp, minimum running frequency for the lamp, and an input voltage for the ballast. Based upon these parameters, the computer program calculates the values for various components of the ballast, including the inductor and capacitor of the output stage, such that the preheat frequency is greater than the ignition frequency, the ignition frequency is greater than or equal to the running frequency, the preheat voltage is less than the maximum preheat voltage, and the difference between the preheat frequency and the ignition frequency is greater than about 5 kHz.

Model and method for high-frequency electronic ballast design

An electronic ballast for a fluorescent lamp which includes a frequency sweep circuit for driving a ballast controller IC at different operating frequencies depending on the operating mode of the fluorescent lamp. The sweep circuit monitors the operating mode of the lamp (e.g., preheat, ignite, running, shutdown) and automatically generates an appropriate variable voltage offset for controlling the lamp. The offset is added to a constant voltage supplied to an input of the ballast controller IC, resulting in a corresponding change in the frequency output by the ballast controller IC (and thus the lamp power). The electronic ballast also includes fault protection logic which monitors signals from the lamp resonant circuit and shuts down the ballast in the event of a fault condition. The fault protection logic also resets the frequency sweep circuit so that the lamp can restart automatically when the fault is corrected.

Universal input warm-start linear ballast

A circuit for igniting and driving a high ignition voltage load includes first and second series coupled switches arranged in a half bridge circuit having an output node. A step-up transformer has a primary winding that is coupled to the bridge circuit at the output node. A load is coupled to the secondary winding to a return potential. Both the first and second switches are capable of being turned on concurrently for a predetermined interval to supply an ignition voltage across the secondary winding sufficient to ignite the lamp.

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Redondo Beach, CA, United States of America

John E Parry