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. 14, 1999
Filed:
Sep. 09, 1997
Motorola Inc., Austin, TX (US);
Abstract
An I/O circuit whose output receives a voltage V.sub.PAD which is temporarily higher than a critical voltage V.sub.DS MAX >V.sub.DS 1 across drain and source of a conducting first N-FET (110, N1) acting as a pull-down device. The first N-FET is protected against hotelectron induced degradation by a serially coupled second N-FET (130, N3). A variable drain-source voltage V.sub.DS 3 is added to V.sub.DS 1. A comparator (150) compares the received voltage V.sub.PAD to a supply voltage V.sub.CC and pulls a gate (G) of the second N-FET (N3) to V.sub.PAD or to V.sub.CC. The conductivity of the second N-FET (N3) is thereby changed so that VPAD is distributed among V.sub.DS 1 and V.sub.DS 2. The comparator (150) conveniently comprises two P-FETs (P1, P2, 160, 170).