When current feedback signal VFB is less than the compensation signal, an output of comparator 202 may be high. When current feedback signal VFB reaches the level of the compensation signal, the output of comparator 202 may transition. An output of RS flip-flop 202 can be determined by the output signal of comparator 202 and clock signal CLK. When the output of RS flip-flop 202 is high, the power switching transistor may be turned on to charge an inductor. Therefore, an inductor current may increase, and current feedback signal VFB can correspondingly increase. When the output of RS flip-flop 202 is low, the power switching transistor may be turned off to discharge the inductor. Therefore, the inductor current can decrease, and current feedback signal VFB may correspondingly decrease. In this way, a substantially constant output current may be achieved by constant current LED driver 200 in accordance with current feedback signal VFB.

According to the above peak current control mode, the pulse-width modulation (PWM) duty cycle of control signal Gate can be controlled by controlling the peak inductor current. When the output voltage changes, a surge of the LED driving current can occur, and this may damage the LED load. In addition, when the PWM dimming signal is relatively small, there can be a surge of the LED driving current, which can make the LED load flicker. Further, when in a light load condition (e.g., the load is shorted), there may be a relatively large steady state loss.