Subscriber line interface circuit providing regulated current
US5138658A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 18, 1991 |
| Grant date | Aug 11, 1992 |
| Priority date | — |
| Expiry date | Nov 18, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02D30/70
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A subscriber line interface circuit that provides regulated current to telephone subscribers in an improved manner reducing the amount of power required to operate while maintaining a constant current source. The current to the telephone subscribers flows through a switching transistor, an inductive storage element, sensing resistors and a transformer. The desired operating characteristic is obtained by cycling the switching transistor. The switching transistor is cycled on at a preset interval causing the telephone subscriber current to flow from the switching transistor. The switching transistor is cycled off in response to an increase in the telephone subscriber current as sensed by the sensing resistors thereby causing the current to flow from the inductive storage element.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.