Patent ID: 8441196

Claim:
A multi-color light emitting device circuit, comprising: a plurality of light emitting device strings of different colors, each light emitting device string including a plurality of light emitting devices of a same color coupled in series, wherein each light emitting device string has one end coupled to a common node for receiving an output voltage, and each light emitting device string generates a corresponding sense signal; a timing control circuit, which determines to turn ON a selected one or none of the light emitting device strings; and a power regulator circuit, when the selected one of the light emitting device strings is ON, the power regulator circuit comparing the sense signal corresponding to the selected light emitting device string with a reference signal, and converting an input voltage to the output voltage according to the comparison result; wherein the number of the light emitting devices of each light emitting device string is determined by an operational voltage of a light emitting device of a color substantially the same as the color of the light emitting devices in that light emitting device string, and wherein at least two of the light emitting device strings have different numbers of the light emitting devices, such that voltage drops of the two light emitting device strings are closer to each other than in a case wherein the two light emitting device strings have the same number of the light emitting devices.