Step-up dc/dc switching converter and semiconductor integrated circuit device

A semiconductor integrated circuit device, wherein

• a signal input terminal;
• a signal output terminal;
• a battery power supply input terminal;
• a direct current voltage input terminal;
• a semiconductor switching device control output terminal;
• a control logic which generates a driving voltage supplied to a semiconductor switching device;
• a power supply circuit which steps-up and outputs a battery voltage input through the battery power supply input terminal;
• a buffer having an output of the control logic as a signal input and having an output of the power supply circuit as a power supply input, performing a level shift of the driving voltage output by the control logic based on the power supply input and then supplying the driving voltage to the semiconductor switching device through the semiconductor switching device control output terminal;
• and
• an amplifier having an input connected to the signal input terminal and an output connected to the signal output terminal and operated with using both of the battery voltage input through the battery power supply input terminal and the voltage generated by the semiconductor switching device input through the direct current voltage input terminal as power supply are integrally formed on a common semiconductor substrate.