A D/A converter has a serial interface. Of the sets of the data representing multiple control signals output from latch circuits, the data representing input data, the data representing strobe signal, and the data representing clock signal are supplied to the D/A converter. A mask circuit is provided in the path supplying the strobe signal. When a parity detection circuit detects a transmission error, the mask circuit masks the strobe signal to be supplied to the D/A converter, thereby preventing the D/A converter from outputting an analog output signal corresponding to the input data.