Patent ID: 9271347
Filing Date: 2016-02-23
CPC Classification: H05B,Y02B

Claim Text:
1. A TRIAC dimmable LED driver circuit comprises an input AC voltage source connected to a rectifier bridge and an LED load, the LED load is connected to an inductor or a transformer, a power MOS transistor, a low voltage MOS transistor and a current sensing resistor, the inductor or transformer includes at least two windings, the first winding is connected to the power MOS transistor, the auxiliary winding is connected to the positive terminal of a supplying diode, the negative terminal of the supplying diode is connected to a supplying capacitor, the LED driver further includes two resistors and an over voltage protection circuit, the resistors are in series and are connected to the auxiliary winding of the inductor or transformer, and the middle point of the resistors are connected to the over voltage protection circuit, the LED driver is characterized in that, a peak current comparator, which is used to compare the voltage between the current sensing resistor and a reference voltage; a maximum on-time timer, which is used to detect the on time of the low voltage MOS transistor, when the voltage on the current sensing resistor is higher than the reference voltage, or the on time of the low voltage MOS transistor reaches the preset time of the maximum on-time timer, the low voltage MOS transistor is turned off.