Bidirectional switch circuit with automatic return-current path selector

An integrated circuit for connection to a first and a second external terminal, said circuit comprising:

• a first unidirectional switch device coupled between the first and second terminals, said first switch device being turned on or off in accordance with a potential difference between said first and second terminals;
• a second unidirectional switch device connected in parallel with the first switch device, said second switch device being turned on or off in accordance with said potential difference between said first and second terminals, the first and second switch devices being connected reverse to each other in a current-forwarding direction thereof;
• return-path selector means connected to said first and second terminals and having an output connected to a power supply device, for providing, in accordance with said potential difference between said first and second terminals, a return-path by which a return-current thereof is fed back from said output to the power supply device, said return-path selector means including a third switch device and a fourth switch device which are turned on selectively such that while one of the third and fourth switch devices is turned on, the other of said third and fourth switch devices is turned off;
• current-flow selector means connected to said first and second switch devices, for receiving an output current of said power supply device, and for causing the output current to be provided unidirectionally to said first and second switch devices;
• and
• bias means connected to said first and second switch devices, for providing said first and second switch devices with bias voltages respectively in response to said output current of said power supply device,
• wherein said first and second switch devices include transistors, and said third and fourth switch devices include transistors which are connected with each other to form a flipflop circuit.