Patent ID: 8716955

Claim:
A light emitting diode (LED) driver comprising: a rectifier, connecting an alternating current (AC) power source and outputting direct current (DC) power; a switching circuit, connecting the DC power of the rectifier, switching the DC power with pulse width modulation (PWM), and having an output end for connecting a load and a feedback control end; and a feedback circuit, connected between the output end and the feedback control end of the switching circuit for controlling a duty cycle of the switching circuit depending on an output current of the output end to keep the output current constant; wherein the feedback circuit comprises a conversion resistor, a comparator and a photocoupler, the conversion resistor connected in a loop formed by the switch circuit and the load, two ends of the conversion resistor are connected to an input end of a comparator, an output end of the photocoupler is connected to the feedback control end of the PWM controller for outputting a feedback signal to the PWM controller, when a voltage fault of the conversion resistor occurs, the comparator controls the photocoupler to open and close.