Patent ID: 9307612
Filing Date: 2016-04-05
CPC Classification: H01L,H05B

Claim Text:
1. A light emitting device driver circuit configured to operably drive a light emitting device circuit which is operative according to a rectified input voltage, the light emitting device circuit including a plurality of light emitting devices connected in series, the plural light emitting devices being divided into a plurality of groups, wherein each group includes at least one light emitting device, the light emitting device driver circuit comprising: a switch module, which includes a plurality of switches, wherein each switch is coupled to a corresponding one of the groups, the switch module being configured to operably determine which of the light emitting devices are turned ON according to the rectified input voltage; a current source circuit, which is coupled to the switch module, and configured to operably provide a light emitting device current according to an adjustment current when at least one of the light emitting devices is turned ON, wherein the light emitting device current is not a constant, and the light emitting device current has substantially the same phase angle as the rectified input voltage for at least a part of time in a cycle period of the rectified input voltage; and a total harmonic distortion (THD) compensation circuit, which is coupled to the current source circuit, and configured to operably generate the adjustment current according to the rectified input voltage; wherein the THD compensation circuit includes: a voltage-to-current conversion circuit, configured to operably convert the rectified input voltage to a THD compensation current; a setting current generation circuit, configured to operably generate a setting current according to a reference signal; and an adder/subtractor circuit, which is coupled to the voltage-to-current conversion circuit and the setting current generation circuit, and configured to operably generate the adjustment current according to the THD compensation current and the setting current.