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:
Oct. 01, 1996
Filed:
Jan. 20, 1995
Kenshiro Arase, Kanagawa, JP;
Akira Nakagawara, Kanagawa, JP;
Sony Corporation, Tokyo, JP;
Abstract
A flash EEPROM, wherein provision is made of an auxiliary bit portion connecting nonvolatile memories in parallel with bit lines of a memory array portion and a spare row decoder for controlling addresses of a redundant memory portion, which records the cumulative number of cycles of rewriting and erasure for each word line in the nonvolatile memories, judges from the stored cumulative number of cycles if the number of cycles of a sector has reached a limit value, and, when reaching it, replaces the word line with a redundant word line so as to prolong the life of the memory even when the cumulative number of cycles of a specific word line has reached a limit value and which stores the data in accordance with different phases when the number of the data '1' or '0' is greater than or less than a predetermined number at the time of writing data and fetches the stored information based on the phase information at the time of reading data so as to reduce the drain disturbances.