| 摘要 |
PURPOSE:To reduce remarkably power consumption by supplying power to a channel board and supplying driving power to an operational amplifier of a voice system, a CODEC and a microprocessor of a signal system only when normal operation is required. CONSTITUTION:Since a photocoupler 9 for supervising subscriber state, latch for reception signals ab, bb from an opposite terminal station device, an alarm ALM and a make-busy switch 11 are all inactivated when the channel board is in an idle state completely, an OR gate 121 of a power supply control circuit 12 is reset, no power is supplied to the amplifier 4, the CODEC5 and the microprocessor 6, the output terminals of them are in a high impedance state substantially, and the level of the terminals is fixed to a low level at all times by pulling down the output terminals for the CODEC5 and the microprocessor 6, no effect is given to other components. When any input of the OR gate 121 is active, the gate is set, a transistor of the circuit 12 is turned on to supply power to each component. |
