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:
Sep. 20, 2005
Filed:
Oct. 11, 2002
Seema Varma, Sunnyvale, CA (US);
Nghiem Nguyen, San Jose, CA (US);
Ha Chu VU, San Jose, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A transceiver circuit includes driver circuits, receiver circuits, and suspend-mode buffers that are arranged to withstand an over-voltage conditions that would otherwise damage those circuits. An over-voltage sense circuit is arranged to detect the over-voltage condition on a data line in the transceiver. Cascode devices are placed in critical points of the various circuits, while voltages are coupled to other critical points such that none of the transistor devices that are coupled to the data lines are damaged by the over-voltage condition. Selector circuits are arranged to couple the highest detected voltages to various transistor wells to prevent forward biasing parasitic diodes in the transistors. Series switching circuits are arranged to break critical conduction paths during the over-voltage condition. The over-voltage protection scheme is suitable for use in integrated USB transceivers.