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:
Jul. 20, 1999
Filed:
Nov. 24, 1998
Tsuyoshi Saitoh, Nagasaki, JP;
Kiyoyuki Shiroshima, Hyogo, JP;
Michio Nakajima, Tokyo, JP;
Masaaki Matsuo, Nagasaki, JP;
Nobuyuki Fujii, Tokyo, JP;
Akira Kitaguchi, Tokyo, JP;
Mitsubishi Electric System LSI Design Corporation, Hyogo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A semiconductor memory device includes memory elements, each maintaining memory contents within a period of time during which a refresh operation is repeated, and a refresh request circuit for making a refresh request. The semiconductor memory device includes refreshing circuits each of which, in response to a refresh request from the refresh request circuit, performs a refresh operation on a different number of memory elements at the same time, and a selecting circuit for selecting one refreshing circuit from among the refreshing circuits according to the number of memory elements included in the semiconductor memory device. The refresh request circuit can change the interval at which it makes a refresh request.