ELECTRONIC BALLAST WITH HIGH POWER FACTOR

摘要

This invention provides an integrated power supply for a controller of an electronic ballast for a fluorescent lamp. The integrated power supply couples output power from the electronic ballast and uses the coupled power to provide power to the controller. In one embodiment, the electronic ballast may include a rectifier for converting an alternating current input voltage into a direct current output voltage, and a circuit including a combined power factor correction (PFC) stage and an inverter, wherein the PFC stage and the inverter share a switch. Also provided is a controller for an electronic ballast. The controller may include a voltage mode or current mode duty ratio controller that controls a duty ratio of a switch of the ballast. The controller and the ballast allow dimming of the fluorescent lamp while maintaining a high power factor.