LED CONTROL METHOD AND STRUCTURE

摘要

An LED(Light Emitting Diode) control method and a system thereof are provided to reduce a cost of the system by forming a substantially unity power factor without a multiplier. In a power factor LED control system(10), a plurality of LEDs(25-28) connected in series receive an LED current(29) between an input and a first common return voltage. An error amplifier forms an error signal corresponding to the LED current. A PWM(Pulse Width Modulation) controller(55) receives the signal corresponding to the LED current and controls the LED current at a substantially unity value. The PWM controller is connected between the first and second common return voltages to receive a driving voltage. The PWM controller does not sense a waveform of an AC input voltage received by the power factor LED control system.