Patent ID: 8247993
Filing Date: 2012-08-21
Classification: G09G,H05B

Abstract:
1. An apparatus for driving a multi-channel light emitting unit including a plurality of light emitting channels connected in parallel with each other, each of the light emitting channels including a plurality of light emitting devices connected in series with each other, the apparatus comprising: a DC/DC converter configured to generate a driving voltage based on an input voltage and supply the driving voltage to an anode of the multi-channel light emitting unit; a current control unit including a plurality of current sources connected between cathodes of the light emitting channels and a ground, and configured to keep currents flowing through the light emitting channels constant; a minimum voltage selection unit configured to detect voltages at the cathodes of the light emitting channels and detect a minimum detection voltage among the detected voltages; a first error detection unit configured to detect an error voltage corresponding to a difference between the minimum detection voltage and a predetermined first reference voltage; and a feedback coupling unit configured to couple an output of the first error detection unit and an input of the DC/DC converter and supply the input voltage according to the error voltage and the driving voltage of the DC/DC converter, wherein the light emitting devices are light emitting diodes, and the first error detection unit comprises a first comparator having a non-inverting input terminal for receiving the minimum detection voltage, an inverting input terminal for receiving the first reference voltage, and an output terminal for outputting the error voltage.