A method of driving an LED can include: (i) controlling a main power switch by a control circuit of an LED driver; (ii) turning on an auxiliary power switch when the main power switch is turned on such that a DC bus voltage is provided to the main power switch through the auxiliary power switch, and the main power switch outputs a driving current to a load; (iii) charging a capacitor by the DC bus voltage through the auxiliary power switch when the main power switch is turned off, where the capacitor is charged until a voltage across the capacitor reaches a predetermined stable voltage; (iv) clamping the voltage across the capacitor at the predetermined stable voltage; and (v) using the clamping voltage across the capacitor as a supply voltage for the control circuit.