Title:
NONVOLATILE MEMORY
Document Type and Number:
WIPO Patent Application WO/2008/029457
Kind Code:
A1
Abstract:
A nonvolatile memory wherein the remaining lives of memory cells can be determined with
high accuracy. There are included a plurality of memory cell groups (111) each
assigned a respective address, arranged for a respective word and used for storing
one word of data; a plurality of dummy cell groups (112) also assigned the respective
addresses and having different ranks of rewrite lives; and a control part (140)
responsive to an externally given command (170) to control the operations of
the memory cell groups (111) and dummy cell groups (112). The control part (140)
comprises a write circuit (141) that, when writing data into a memory cell group
(111) having a given address, also writes the data into a dummy cell group (112)
having the same address at the same time; and a life determining circuit (142)
that determines whether each dummy cell group (112) can be successfully accessed,
thereby determining an estimated number of past write operations.
Inventors:
ISE, Masahiro (1-1 Kamikodanaka 4-chome, Nakahara-ku, Kawasaki-sh, Kanagawa 88, 2118588, JP)
Application Number:
JP2006/317653
Publication Date:
March 13, 2008
Filing Date:
September 06, 2006
Export Citation:
Assignee:
FUJITSU LIMITED (1-1 Kamikodanaka 4-chome, Nakahara-ku Kawasaki-sh, Kanagawa 88, 2118588, JP)
富士通株式会社 (〒88 神奈川県川崎市中原区上小田中４丁目１番１号 Kanagawa, 2118588, JP)
富士通株式会社 (〒88 神奈川県川崎市中原区上小田中４丁目１番１号 Kanagawa, 2118588, JP)
International Classes:
G11C16/02; G11C16/04; G11C29/04; G11C16/02; G11C16/04; G11C29/04
Attorney, Agent or Firm:
YAMADA, Masaki et al. (Pelican Building 4th Floor, 3-3 Nishi-shimbashi 3-chome, Minato-k, Tokyo 03, 1050003, JP)
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