| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the buffer power consumption of CMOS device constitution and to reduce the power by converting the downstream direction signals an of-line state unit into a fixed value signal. SOLUTION: The standby system line interface unit 12 of an off line state converts a reception signal from a standby system transmission line into the fixed value signal in a fixed value output circuit 123 and transmits it to a switch unit 10 through a transmission buffer 122. Then, it is received through a reception buffer 103. On the other hand, a present system line interface unit 11 in an on state receives a reception signal from present system transmission line as it is through a transmission buffer 112. The respective signals of the units 11 and 12 are controlled by a line protection control part 104 in a selection circuit 105, select the signal of the unit 11 and they are transmitted as the downsream direction signals. Since the fixed value signal is inputted to the buffer related to the unit 12, the buffer does not execute a switching operation, current does not flow and power can be reduced. |
