SEMICONDUCTOR INTEGRATED CIRCUIT AND OPERATION METHOD THEREOF
First Claim
1. 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, andwherein 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.
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Accused Products
Abstract
A DC-DC converter supplies an output voltage to a plurality of channels of a light emitting device array in common. A current driver has a plurality of driver units which drive the channels. Each of the driver units includes a drive transistor and a detector which detects an abnormality of a drive current. A logic unit generates digital data in response to a plurality of detection signals and supplies the same to a D/A converter. An analog reference voltage of the D/A converter is supplied to the DC-DC converter. The logic unit executes a calibration operation which determines digital data for setting the minimum output DC voltage at the normal operation of all the channels by sequential updating of the digital data.
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Citations
20 Claims
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1. A semiconductor integrated circuit capable of driving a plurality of channels of a light emitting device array in parallel, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An operation method of a semiconductor integrated circuit capable of driving a plurality of channels of a light emitting device array in parallel, comprising the steps of:
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causing the semiconductor integrated circuit to comprise a DC-DC converter, a current driver, a logic unit, and a D/A converter; causing the DC-DC converter to be 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; causing the current driver to comprise a plurality of driver units capable of driving a plurality of other ends of the channels; causing each of the driver units to comprise 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; causing the logic unit to be capable of generating digital data in response to a plurality of detection signals generated from the detectors of the driver units of the current driver and supplying the same to an input terminal of the D/A converter; causing the D/A converter to be 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 causing the logic unit to perform, 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. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification