Patent ID: 8581509

Claim:
A driving circuit having a power factor correction (PFC) function, adapted to drive a LED (light emitting diode), the driving circuit comprising: a power converter, receiving AC power and to convert the AC power to DC power; a harmonic wave generator, coupled to the power converter and to generate a harmonic wave from the DC power; a voltage divider, coupled to the harmonic wave generator and decreasing a voltage level of the harmonic wave to generate a comparing signal; and a modify element, coupled to the voltage divider and receiving the compare signal to compare with a feedback current signal of the LED and regulate the DC power accordingly for power-supplying the LED stably; wherein the modify element comprises: a first comparator, receiving the harmonic wave and the feedback current signal to execute a first comparison operation; a second comparator, receiving the feedback current signal and an internal working voltage to execute a second comparison operation; an OR gate, coupled to the first comparator and the second comparator, and generate a modify signal according the first comparison operation and the second comparison operation; and a duty-cycle controller, coupled to the OR gate and regulating the DC power according to the modify signal.