| 摘要 |
A driver for driving at least one string of LEDs with a rectified AC voltage is provided, comprising input terminals for supplying a rectified AC voltage, a control circuitry being supplied with a signal indicating the amplitude or the phase of the AC voltage, and a switching network comprising switches, each switch being arranged for selectively shunting or activating a substring of one or more LEDs of the LED string, wherein the control circuitry is designed to control each of the switches independently such that the combined forward voltage of the activated substrings of LEDs follows the amplitude of the rectified AC voltage in incremental steps, characterized in that the control circuitry is designed to alternate at least 2 active substrings of LEDs having the same combined forward voltage during the time period of one step. |
