Patent ID: 7245089

Claim:
A LED driver, comprising, a inductor having a first winding connected in series with a LED; a switch, connected in series with the LED and the first winding of the inductor for controlling a LED current; a control circuit, coupled to a second winding of the inductor for generating a control signal in response to a reflected signal of the inductor and the LED current; and a diode, coupled in parallel to the LED and the inductor for discharging the energy of the inductor through the LED; a first resistor, connected in series with the switch for sensing the LED current and generating a LED current signal coupled to the control circuit; and a second resistor, connected to the control circuit for determining a slope of the adjustment, in which the slope represents the change of a first threshold versus the change of the reflected signal of the inductor; wherein the control signal controls the switch and the LED current, and the switch is turned off once the LED current is higher than the first threshold; the switch is turned on after a period of a programmable delay time once the energy of the inductor is fully discharged.