ISDN BASIC INTERFACE STATION POWER FEEDING/POWER RECEIVING CIRCUIT

PROBLEM TO BE SOLVED: To realize a communication function which is not restricted to the basic call function of a terminal(TE) even in a situation where external power is not supplied by receiving the local power feeding current of reverse polarity, which is power-fed from an exchange, with a designated input resistance value. SOLUTION: A local power feeding/power receiving circuit 10 is connected in series to the line terminal equipment(NT) 30 connected to a U point interface and a power receiving part input resistance value setting part 12 sets an input series resistance value, and the power feeding current of the reverse polarity (inverse polarity: DC potential is higher in L2 line compared to an L1 line), which is power-fed from the exchange (LT) 20 with the input DC resistance value, is received. It is fed to the reverse reception part 31 of NT 30. A forward current bypass part 14 by-passes forward current. It is by-passed by an AC component/AC signal bypass part 15 and the AC component is prevented from flowing to a reverse power feeding/power receiving part 13. The input resistance value is automatically set in the power receiving part input resistance value setting part 12 based on a DC current value which is measured in the reverse current measuring part 11.