Patent ID: 8169161

Claim:
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; and a multi-input error amplifier having an output node and a plurality of input nodes for receiving a plurality of input signals, wherein each one of the plurality of input nodes is coupled to the input node or the output node of a respective one of the plurality of current regulators, wherein the multi-input error amplifier is configured to generate an error signal at the output node of the error amplifier, wherein the error signal is related to an arithmetic mean of the plurality of input signals received by the error amplifier.