Patent ID: 8525423

Claim:
Circuitry for driving a plurality of LED strings, comprising: a plurality of current regulating circuits in a plurality of groups, wherein each of the current regulating circuits is coupled to one of said LED strings, and is configured to regulate a current flowing through a corresponding LED string; a plurality of control circuits, wherein each control circuit is coupled to the corresponding group of current regulating circuits, and wherein each of the control circuits is configured to generate a control signal based on output voltage of the corresponding group of current regulating circuits, and each control circuit comprises: a voltage selecting circuit coupled to the corresponding group of current regulating circuits, wherein the voltage selecting circuit is configured to select a minimum output voltage of the corresponding group of current regulating circuits; an error amplifying circuit coupled to the voltage selecting circuit, wherein the error amplifying circuit is configured to amplify a difference between the minimum output voltage and a reference voltage to generate the control signal; a voltage converter electrically coupled to the LED strings and to the control circuits, wherein the voltage converter is configured to provide a DC driving voltage for driving the LED strings, and is configured to regulate the DC driving voltage based on the control signals; a plurality of compensation networks each coupled between an output end of the error amplifying circuit and ground, and wherein the compensation networks individually include an output configured to generate a compensation signal based on the corresponding control signal; and a compensation signal selecting circuit electrically coupled to the output of the compensation networks, wherein the compensation signal selecting circuit is configured to select a maximum value among the compensation signals, and wherein an output of the compensation signal selecting circuit is coupled to the voltage converter.