| 摘要 |
PURPOSE:To enable a terminal to be operated even when a cutoff state is generated at an AC 100V power source supplied to a digital circuit terminating device. CONSTITUTION:The fact that the cutoff state occurs at the AC 100V power source is detected by an AC cutoff detecting circuit 2, and a detection signal is supplied to an internal processing circuit 1 in the digital circuit terminating device 6. The internal processing circuit 1 switches the movable contact (c) of a switch SW1 to the fixed contact (b) side based on the detection signal. Thereby, a power source can be supplied from a backup power unit 5 to the internal processing circuit 1. Also, the power source from the backup power unit 5 can be supplied to the terminal 8 via the internal processing circuit 1 and a metallic line 9. |
