Patent ID: 9258861
Filing Date: 2016-02-09
CPC Classification: H05B

Claim Text:
1. An apparatus for driving multi-color LED strings, comprising: an input voltage; a multiplexing switch having first, second and third inputs and an output; a red LED string having a plurality of red LEDs controlled by a corresponding switching circuit, said red LED string having a positive end connected to said input voltage and a negative end connected to said first input of said multiplexing switch; a green LED string having a plurality of green LEDs controlled by a corresponding switching circuit, said green LED string having a positive end connected to said input voltage and a negative end connected to said second input of said multiplexing switch; a blue LED string having a plurality of blue LEDs controlled by a corresponding switching circuit, said blue LED string having a positive end connected to said input voltage and a negative end connected to said third input of said multiplexing switch; a current source having a first end connected to said output of said multiplexing switch and a second end connected to ground; a controller receiving a color setting signal and sending a plurality of controlling signals to each of the switching circuits, and multiplexing signals to control said multiplexing switch; wherein said controller controls respective numbers of LEDs connected in series in the red, green and blue LED strings through the corresponding switching circuits, and the duration that said current source is turned on for each of the red, green and blue LED strings according to said color setting signal.