| 摘要 |
PURPOSE:To limit feeding immediately when a load side is short-circuited and an overcurrent flows by turning off a feeding transistor(TR) by a forced supply stop and disconnecting the 2nd overcurrent detection circuit so as to interrupt completely the current thereby stopping the feeding. CONSTITUTION:With a forced supply stop signal SD setting the presence of power supply by a control circuit 2 forcibly sent, a power supply TR of a feeding limit circuit 3 is turned off by a signal via a gate circuit 7 and a feeding control circuit of a subscriber circuit is switched temporarily into a minute current circuit through a path comprising a subscriber terminal equipment 10, the 1st overcurrent detection circuit 4, a current interruption circuit 9, the 2nd overcurrent detection circuit 5 and ground from a power supply VBB. However, an SD signal from the control circuit 2 is given to the current interruption circuit 9 by an inverter via the 2nd delay circuit 8, then the current interruption circuit 9 is operated to interrupt the minute current circuit. Thus, the subscriber current supply circuit is completely interrupted. |
