| 摘要 |
PURPOSE:To offer a subscriber circuit with less power consumption while using a single power supply by providing a DC-DC converter to a talking current supply circuit. CONSTITUTION:The DC-DC converter 8 is connected to one terminal of the talking current supply circuit 7 comprising an output line of a talking current supply power source 15. A talking current supply line through the DC-DC converter 8 is connected to a subscriber supervisory circuit 4. When a subscriber 2 is in the state of no call, since a talking line 3 forms no loop, no talking current flows. When the subscriber 2 makes a call, a current flows to the talking line 3, it is an input to the DC-DC converter 8, which is started and each voltage is generated to output supply lines 9-13. Thus, the subscriber supervisory circuit, a CODEC6 and a control circuit 14 start operation. The power required for the subscriber circuit 1 is only the talking current supply source 15 in this way and no power is consumed when the subscriber 2 makes no call. |
