Semiconductor circuit device

摘要

A semiconductor circuit device, in which an output device is driven by inputting a direct current voltage source having a predetermined potential difference on the high potential side relative to a system ground and a power supply having a potential varied with time relative to the system ground. The semiconductor circuit device includes a voltage conversion circuit which converts an input signal having an amplitude between the system ground and the direct current voltage source into a converted signal having an amplitude between an internal ground and an internal power supply, and outputs the converted signal. The internal ground is controlled to have a potential varied with time relative to the system ground, and the internal power supply is controlled to change according to a change of the internal ground and have the predetermined potential difference on the high potential side when the internal ground has a fixed potential. A selector circuit selects and outputs the input signal and the converted signal according to the potential of the internal ground.