Combined loop current sink, battery detector, and ringing detect

Details Combined loop current sink, battery detector, and ringing detect Combined loop current sink, battery detector, and ringing detect

1997-05-15

1999-11-09

Zele, Krista

Telephonic communications

Supervisory or control line signaling

Using line or loop condition detection

379377, 379382, 379399, H04M 100

Patent

active

059828781

ABSTRACT:
A combined loop current sink, battery detector, and ringing detector circuit as used in a channel unit at a telephone central office connection to a digital loop carrier circuit, to provide off-hook and on-hook signaling to analog switching circuits, and to simultaneously receive normal battery and ringing signals from the analog switching circuits. The combined circuit includes tip and ring connections to the digital loop carrier circuit to provide telephone service, a loop input controlled by logic circuits, at the telephone central office, and a battery output connected to the logic circuits. A first optocoupler, is connected to the loop input and also to ground, for providing a floating voltage coupling for the loop input to the circuit. A second optocoupler, is connected to the battery output and also to ground, for providing a floating voltage coupling for the circuit output. A transistor circuit has an input coupled to the first optocoupler and an output coupled to the second optocoupler. The logic circuits send an on-hook signal by applying a zero volt ground signal to the loop input so that no current flows through the first optocoupler, and an off-hook signal by a positive volt signal to same input so current flows through the first optocoupler.

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