POWER FACTOR CORRECTION CIRCUIT AND METHOD OF AC DIRECT LIGHT APPARATUS

摘要

A power factor-improving circuit of an alternating current (AC) direct lighting device comprises: a valley signal generating part for receiving an AC input voltage, which has gone through full-wave rectification, and comparing an inner reference voltage with the AC input voltage to generate a valley signal; a reference voltage control part for receiving the generated valley signal, detecting the frequency of the AC input voltage by counting inner clocks, and determining the frequency of a driving electric current to control a reference voltage based on the determined frequency of the driving electric current; and a reference voltage control clock generating part for generating a pulse width modulation signal associated with the amplitude of the reference voltage, and generating a reference voltage control clock based on the generated pulse width modulation signal and the controlled reference voltage. Therefore, the power factor-improving circuit of an AC direct lighting device can improve the power factor of a circuit by controlling the phase of a driving electric current and adjusting the change of the reference voltage.