Switch apparatus

A switch apparatus comprising:

• a main switch that is connected between a first terminal and a second terminal and electrically connects or disconnects the first terminal and the second terminal according to gate voltage applied to a gate terminal;
• a voltage output unit that has a voltage divider including a first voltage-division resistance on the first terminal side and a second voltage-division resistance whose one end is connected to the second terminal side, and outputs voltage corresponding to voltage of the first terminal and voltage of the second terminal in response to the main switch entering a connected state;
• a buffer that outputs voltage following output voltage of the voltage output unit in a connected state of the main switch;
• and
• a switch control circuit that supplies first voltage corresponding to output voltage of the buffer to the gate terminal of the main switch, and supplies a second voltage corresponding to output voltage of the buffer to a bulk terminal of the main switch;
• wherein the voltage output unit:
• outputs an average voltage of voltage of the first terminal and voltage of the second terminal in response to the main switch entering a connected state, and
• outputs voltage corresponding to either the voltage of the first terminal or the voltage of the second terminal and to first reference potential in response to the main switch entering a disconnected state;
• wherein the voltage output unit has:
• a first output resistance having one end that is connected between the first voltage-division resistance and the second voltage-division resistance and another end that outputs output voltage of the voltage output unit,
• a second output resistance having one end that is connected to the other end of the first output resistance and another end to which the first reference potential is supplied, and
• a third sub-switch that is provided between the second output resistance and the first reference potential, and enters a disconnected state in response to the main switch entering a connected state, and enters a connected state in response to the main switch entering a disconnected state.