Patent ID: 8536806

Claim:
A semiconductor integrated circuit capable of driving a plurality of channels of a light emitting device array in parallel, comprising: a DC-DC converter; a current driver; a logic unit; and a D/A converter, wherein the DC-DC converter is capable of supplying an output DC voltage generated by stepping-up or stepping-down an input DC voltage to a plurality of one ends of the channels in common, wherein the current driver comprises a plurality of driver units capable of driving a plurality of other ends of the channels, wherein each of the driver units comprises a drive transistor which drives the other end of each of the channels of the light emitting array, and a detector capable of detecting an abnormality of a drive current of the drive transistor, wherein the logic unit is capable of generating digital data in response to a plurality of detection signals generated from the detectors of the driver units of the current drive and supplying the same to an input terminal of the D/A converter, wherein the D/A converter is capable of generating an analog voltage in response to the digital data and supplying the same to the DC-DC converter as a reference voltage, and wherein the logic unit performs, according to sequential updating of the digital data, a calibration operation which determines the digital data for setting the minimum output DC voltage at a normal operation of all the channels, in which none of the detection signals generated from the detectors indicates the abnormality of the drive current.