Jingwei Lin

US Patent:

61887641, Feb 13, 2001

Filed:

May 27, 1998

Appl. No.:

9/085894

Inventors:

Jingwei Lin - Saratoga CA

Assignee:

ActionTec Electronics, Inc. - Sunnyvale CA

International Classification:

H04M 1100

US Classification:

379412

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.