DIMMABLE HIGH POWER FACTOR HIGH-EFFICIENCY ELECTRONIC BALLAST CONTROLLER INTEGRATED CIRCUIT WITH AUTOMATIC AMBIENT OVER-TEMPERATURE SHUTDOWN

摘要

An embodiment of the invention relates to an electronic ballast dimmer, of high efficiency and of high power factor which comprises on a single chip (300) with integrated circuits a shunt regulator (302), a reference voltage ( 306), high temperature cutout (316), undervoltage lockout (304), start and restart timer (314), variable oscillator (322), mode control (320) , an operational amplifier (318) for receiving a signal proportional to the lamp current and for controlling the variable oscillator or the pulse rate of the pulse output in a closed loop servo drive, and active correction the power factor which comprises an analog multiplier (12) for receiving an AC voltage and an AC sample and multiplying them to provide a comparison with a DC voltage. The comparison provides a control signal from a field effect MOS device (28), which connects an adjustable converter transformer (18) to actively correct the power factor at a rate determined by the oscillator.