To obtain an A/D converted value with high precision even if reference voltages used for correction processing are varied.

Reference voltages V1, V2, and V3 generated by a reference voltage generating circuit 5 are actually measured in an IC inspection stage, and ideal A/D converted values corresponding to the measured reference voltages V1, V2, and V3 are computed and written as reference data V1D, V2D, and V3D to a memory 14. A correction control circuit 13 writes an A/D converted value Vref-A, Vref+A, V1A, V2A, or V3A output from an A/D converter 4 as correction data to a register 15 when an input voltage Vin is a reference voltage Vref-, Vref+, V1, V2, or V3, and corrects the A/D converted value output by the A/D converter 4 for a signal voltage Vs by using the correction data, reference data, and a prescribed value (000H, FFFH).

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