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. 06, 1999
Filed:
Mar. 25, 1996
Robert James Johnston, Fair Oaks, CA (US);
Joseph Harold Salmon, Placerville, CA (US);
Intel Corporation, Santa Clara, CA (US);
Abstract
A method and apparatus for reducing leakage currents in a high voltage tolerant I/O buffer. An I/O buffer designed to tolerate high external voltages by blocking such voltages at a passgate in a p-output path that uses a device between a p-driver gate node and a p-gate node of the passgate to ensure that the p-transistor of the passgate is turned on when the p-driver is driving the pad high. A second device isolates the p-gate node of the passgate from the pad until a pad voltage reaches a predetermined level. Once the pad voltage reaches the predetermined level, the device drives the voltage at the p-gate node of the passgate to that of the pad. Maintaining the p-transistor of the passgate on while the p-driver is driving the pad high allows a rapid hard shut-off of the p-driver as the I/O buffer tri-states the pad. Additionally, the second device maintains the necessary voltage protection by insuring a hard shut-off of the p-transistor of the passgate when the voltage at the pad reaches a predetermined level.