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:
Mar. 18, 1986
Filed:
Jun. 20, 1984
Philip T Martin, Raleigh, NC (US);
ITT Corporation, New York, NY (US);
Abstract
A lightning protection circuit for a digital subscriber loop interface has a loop interface transformer primary, connected across the TIP and RING terminals of the DSL interface, with a split winding. The split primary windings are balanced to minimize induced secondary voltages in the event of common mode lightning signals. Matched TIP and RING resistors limit the lightning current flowing to lightning ground. Back-to-back zener diode pairs across each split winding, and a capacitor connecting the split windings, limit the voltage across the windings in the event of differential lightning signals. The capacitor absorbs most of the lightning energy, rather than the secondary windings or the resistors. Back-to-back zener diode pairs across each secondary winding provide further lightning protection by limiting the energy absorbed by the transmit and receive circuitry. A resistor and diode configuration is used to protect the DSL interface analog switch and power supplies of the receive circuitry, and a diode may be used to protect the -5 volt power supply of the transmit circuitry.