Circuitry for driving light emitting diodes and associated methods

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;
• and wherein
• when the minimum output voltage is higher than the reference voltage, the error amplifying circuit has a first gain;
• when the minimum output voltage is lower than the reference voltage, the error amplifying circuit has a second gain;
• and
• the first gain is greater than the second gain.

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;
• and wherein
• when the minimum output voltage is lower than the reference voltage, the error amplifying circuit is configured to limit the corresponding control signal at a first threshold;
• when the minimum output voltage is higher than the reference voltage, the error amplifying circuit is configured to limit the corresponding control signal at a second threshold;
• and
• the first threshold is greater than the second threshold.

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;
• and wherein
• the voltage selecting circuit comprises a plurality of diodes each having a cathode and an anode, wherein each of the cathodes of the diodes are coupled to an output of the corresponding current regulating circuit, and wherein the anodes of the diodes are electrically coupled together to output the minimum voltage.

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;
• and
• a plurality of compensation networks each electrically coupled between an output of the corresponding error amplifying circuit and ground, and wherein the compensation networks have a common output configured to generate a compensation signal based on the control signals, and wherein the output of the compensation networks is coupled to the voltage converter.