ELECTRONIC BALLAST FOR LIGHTING UNIT AND LIGHTING APPARATUS

摘要

This invention provides an electronic ballast for a lighting unit, which comprises a Power Factor Correction (PFC) circuit, an inverter, and a control circuit for controlling startup of the inverter, wherein the control circuit is coupled between the PFC circuit and the inverter and includes: a switching device coupled in a startup loop for the inverter; a unidirectional conductive device coupled between a PFC power supply circuit for providing an operation current for a PFC controller of the PFC circuit and an input of the PFC controller, for preventing a startup current flowing through the PFC circuit from triggering the switching device; and a triggering device coupled to the switching device and a connection point between the unidirectional conductive device and the PFC power supply circuit, for controlling switch-on and -off of the switching device. According to this invention, the startup of the inverter is later than the startup of the PFC circuit by use of the controller, so that the output voltage can reach the rated value meeting the startup requirements of the lighting unit such as a discharge lamp, thereby prolonging the service life of the discharge lamp.