It is aimed at being capable of easily changing a power supply startup procedure and complying with various display devices. A power supply circuit is provided between an instruction register of a liquid crystal driver and a power supply unit. The power supply unit is not directly supplied with a setting value registered to the instruction register from a microprocessor unit. The microprocessor unit writes setting values to the instruction register without need for the time axis. To turn on the power, the time is measured inside the power supply sequencer. Set values are sequentially input to the power supply unit. The instruction register should be also capable of registering an input timing.