Electronic circuits for driving series connected light emitting diode strings

An electronic circuit for driving a plurality of series connected light emitting diode strings with a controllable DC-DC converter, the electronic circuit comprising;

• a plurality of current regulators, each having a respective input node and a respective output node, the input node or the output node coupled to an end of a respective one of the plurality of series connected light emitting diode strings, wherein each current regulator is configured to pass a respective predetermined current through the respective one of the plurality of series connected light emitting diode strings to which it is coupled;
• a plurality of switches, each having a respective input node, a respective output node, and a respective control node, wherein each one of the input nodes of the plurality of switches is coupled to the input node or the output node of a respective one of the plurality of current regulators, wherein the output nodes of the plurality of switches are coupled together resulting in a composite signal;
• a digital channel select circuit coupled to the control nodes of the plurality of switches and configured to close each one of the plurality of switches sequentially and periodically;
• and
• an error amplifier having an input node and an output node, wherein the input node of the error amplifier is coupled to receive the composite signal, wherein the error amplifier is configured to generate an error signal at the output node of the error amplifier.