| 摘要 |
PURPOSE:To reduce the driving power consumption of the switch, by supervising a current by the current supervisory circuit as soon as the switch is driven, confirming that the switch is driven, by a current flowing into the circuit intermittently, and stopping driving the switch by the said fact. CONSTITUTION:In case ''call'' is being made, a logical signal ''1'' is input as input signals 13, 15, and it is held by the holding circuits 10, 12. The DC supplying circuit 8 is driven by the holding circuit 12, in order that a current is supplied to the trunk line 2. In this state, an output of the current supervisory circuit 7 is logical ''0'', and the gate 21 is opened and the reverse direction switch 4 is driven. As a result, the incoming trank 1 starts to make a current flow into the trunk line 2 through the outgoing trunk 3. Subsequently, when it reaches the circuit time constant, the circuit 7 detects a current flow, and stops driving the reverse direction switch 4. Since the switch 4 has the self-holding function, however, it remains conducting. Also, in case of driving the forward direction switch 5, too, the same control is executed. |
