ELECTRONICALLY DIMMABLE BALLASTER FOR A HIGH-INTENSITY DISCHARGE LAMP

摘要

A dimmable electronic ballast for an HID lamp includes a rectifier stage for rectifying an AC input and providing a rectified DC output, a power factor correction stage for modifying a power factor of the AC input and for providing an increased voltage DC output from the rectified DC output, an electronic ballast control circuit for providing a driving signal comprising a pulse train for controlling a switching operation of an output switch stage driving the HID lamp; the output switch stage having at least one electronic switching element coupled to the increased voltage DC output for providing a pulsed power signal to the HID lamp to power the lamp, the electronic ballast control circuit having a feedback input comprising a signal related to the power dissipated by the HID lamp for maintaining the power at a desired level, the desired level being set by a dimming control input to the electronic ballast control circuit. The circuit provides high frequency power, typically above 50 kHz, to the HID lamp.