| 摘要 |
PURPOSE:To save useless power consumption by interrupting phantom feeding to a DC/DC converter in the standby state of an ISDN terminal equipment and activating the phantom feeding to the DC/DC converter in the active state. CONSTITUTION:When an ISDN terminal equipment such as a telephone set is in the standby state, since a signal from an ISDN line 21 is not received, a detection signal S1 of a reception signal detection circuit 11 is not outputted and a relay 12 is deenergized. On the other hand, since the telephone set is hooked on, a switch 13 is opened and the feeding to a DC/DC converter 14 is stopped. Thus, when the telephone set is in the standby state, the relay 12 and the switch 13 are opened and the feeding to the DC/DC converter 14 is interrupted and when the telephone set is in the operating state, the switch 13 or the relay 12 are closed and the feeding to the DC/DC converter 14 is implemented. |
