Patent ID: 8362711

Claim:
An alternating-current (AC) light-emitting diode (LED) apparatus, comprising: a rectifier configured to rectify a power AC voltage to generate a rectified voltage; a controller configured to monitor the rectified voltage; a plurality of serial-connected LEDs electrically coupled between the rectified voltage and a ground; a plurality of switches corresponding to at least a portion of the LEDs respectively, wherein one terminal of each switch is electrically coupled to one electrode of the corresponding LED or LEDs; and a difference unit coupled to receive two ends of a string of the LEDs to obtain a voltage difference across the string of LEDs, wherein the obtained voltage difference is fed to the controller; wherein the switches are controlled by the controller according to the rectified voltage, the controller controls an LED current flowing through the LEDs, wherein current distribution through the LEDs is approximately reversed to current distribution drawn from the power AC voltage.