The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 26, 2005
Filed:
Dec. 17, 1998
Martin R. Handforth, Kanata, CA;
Gerard J. Hupe, Nepean, CA;
Donald S. Mcginn, Ashton, CA;
Rolf G. Meier, Carp, CA;
Canute Planthara, Ottawa, CA;
Raymond K. Wong, Kanata, CA;
Martin R. Handforth, Kanata, CA;
Gerard J. Hupe, Nepean, CA;
Donald S. McGinn, Ashton, CA;
Rolf G. Meier, Carp, CA;
Canute Planthara, Ottawa, CA;
Raymond K. Wong, Kanata, CA;
Nortel Networks, Ltd., St. Laurent, CA;
Abstract
A protection arrangement for a telephone subscriber line interface circuit is disclosed. The arrangement is particularly useful for protecting an electronic telephone set from over-voltage and over-current fault conditions. The arrangement provides a FET that operates in saturation mode to connect an office battery to the subscriber line under normal operation. The FET also provides isolation capabilities for protecting the line circuit from an over-current condition on the subscriber line. Over-voltage protection is provided by way of an isolation relay between the line circuit and the subscriber line. Both the FET and isolation relay are operated by a controller that uses timers in the methods of over-voltage and over-current protection that it performs. A further capability of the arrangement is that it resets itself after the fault condition has ended. This feature is particularly useful in the case of fault conditions of short duration.