Patent ID: 8269429

Claim:
An apparatus for driving a light emitting unit, the apparatus comprising: a DC/DC converter unit configured to generate driving power based on an input voltage and supply the generated driving power to an anode of the light emitting unit including a plurality of light emitting devices; a current source configured to control a current level of a current flowing through the light emitting unit to keep the current constant; a feedback circuit unit configured to detect a voltage at a cathode of the light emitting unit; and a feedback coupling circuit unit coupling an output terminal of the feedback circuit unit and an input node of the DC/DC converter unit to supply the input voltage to the DC/DC converter unit according to the voltage detected by the feedback circuit unit and an output voltage of the DC/DC converter unit, wherein the light emitting devices are light emitting diodes, and the feedback coupling circuit unit comprises: a first resistor connected between an output node of the DC/DC converter unit and the input node of the DC/DC converter unit; a second resistor connected between the input node and a ground; and a third resistor connected between the output terminal of the feedback circuit unit and the input node.