Over-voltage protection circuit for use with a telephone appliance
US6188764A · kind A · utility
17Cited by
15References
17Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | May 27, 1998 |
| Grant date | Feb 13, 2001 |
| Priority date | — |
| Expiry date | May 27, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M2207/203
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Over-voltage protection circuitry for use with a PCMCIA modem card or a mobile modem is disclosed. The protection circuitry detects excessive voltage between the tip and ring lines of a telephone subscriber loop when the modem is "off-hook", and immediately places the modem "on-hook", protecting the line interface circuitry, when the over-voltage condition is detected. The over-voltage protection circuitry of the present invention may share common components and signal lines with the modem's ring-detection circuitry, and may be implemented using a minimal number of additional components.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.