Patent ID: 7525369

Claim:
A semiconductor circuit apparatus, comprising: a voltage converter connected to a single power supply, for outputting one selected from a power supply voltage of the power supply and a converted voltage converted from the power supply voltage; a voltage conversion controller for controlling whether to output the power supply voltage or the converted voltage from the voltage converter; a signal output section connected to the voltage converter, for selecting and outputting a signal output from the voltage converter and a reference voltage in accordance with an input signal; and a step-down section for stepping down a voltage output from the voltage converter, wherein whether to perform voltage step-down operation in the step-down section is controlled in accordance with a reduction/non-reduction selection signal, wherein: the voltage converter generates the converted voltage by using a reference voltage and the power supply voltage that are input alternatively, the voltage conversion controller controls the voltage converter to output the power supply voltage by supplying a fixed voltage to the voltage converter, and when outputting the converted voltage, the voltage converter stores a voltage while the signal output section outputs the reference voltage and supplies the converted voltage to the signal output section while the signal output section outputs the converted voltage.