Subscriber line interface circuit with power-down mode
USRE35582E · kind E · reissue
Assignee
Inventors
Key dates
| Filing date | Feb 26, 1996 |
| Grant date | Aug 12, 1997 |
| Priority date | — |
| Expiry date | Feb 26, 2016 |
Classification
- Technology area (CPC —)General
Abstract
A method of lowering the power absorbed by an interface circuit, in the "power-down" state thereof, as incorporated to a telephone exchange and connected to a telephone subscriber line, being of a type which comprises a monitoring circuit portion connected between the line and the exchange. The method involves the steps of, PA1 detecting the polarization level of a conductor in the line, PA1 comparing that level with a reference value by means of a comparator having an input connected to the line and an output connected to the input of the monitoring circuit portion, PA1 switching the interface circuit to a standby state on a higher level than the reference value being sensed, PA1 once again detecting the polarization level of the line, this time through the interface circuit, and PA1 activating the telephone exchange when, on completion of the second detection step, the polarization level stays above the reference value.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.