Telephone set circuit including an overvoltage protection

Details Telephone set circuit including an overvoltage protection Telephone set circuit including an overvoltage protection

1988-06-01

1990-01-23

Ng, Jin F.

Telephonic communications

Subscriber line or transmission line interface

Protective circuit

379387, H04M 100

Patent

active

048963526

ABSTRACT:
In order to insure the protection of telephone set circuits when overvoltages generated from the telephone line occur, without impairing the operation of the set when hooking off the handset, the instant invention provides for a protection circuit incorporated into the integrated circuit fulfilling the main functions of the set. This protection circuit limits the current used by the integrated circuit top a first value (120 milliamperes) for the 250 milliseconds which follows the hooking off of the handset, then to a second value (60 milliamperes). If an overvoltage occurs, generated from the line, a time-delay of 100 milliseconds occurs before assigning a supplementary current limitation to 30 milliamperes. According to the invention, this time-delay may be as short as 100 milliseconds since it is initiated only if the first time period of 250 milliseconds is completed.

REFERENCES:
patent: 4268723 (1981-05-01), Taylor
patent: 4475012 (1984-10-01), Coulmance
patent: 4626626 (1986-12-01), Coulmance
patent: 4636588 (1985-02-01), Nakayama et al.

Affiliated with

Also associated with

Rating

Telephone set circuit including an overvoltage protection does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Telephone set circuit including an overvoltage protection, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Telephone set circuit including an overvoltage protection will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-649563