The PD4711B is a high-voltage silicon gate CMOS line driver/reciever conforming to the EIA/TIA-232-E standard. It can operate with a single +5 V power source because it is provided with a DC-DC converter. In addition, this line driver/receiver has many ancillary functions, including output control, threshold select, and standby functions. Because the PD4711B is provided with two output driver circuits and two receiver circuits, it can constitute an RS232 interface circuit with a single chip.