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. 27, 1993
Filed:
Jul. 19, 1991
Mitsuo Isobe, Tama, JP;
Hisashi Ueno, Kawasaki, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
A refresh control circuit for a pseudo static random access memory includes a refresh control signal output circuit for outputting a refresh control signal to accomplish refresh control of the pseudo static random access memory, and includes a delay circuit. A first chip enable signal from a control device such as a MPU is delayed by the delay circuit and outputted as a second chip enable signal for the PSRAM. As the first chip enable signal level changes from a selection level to a non-selection level, the refresh control signal level changes to a non-refresh level. This state is maintained for a predetermined period. After the second chip enable signal changes from the selection level to the non-selection level, the refresh control signal returns from the non-refresh level to the refresh level. Thus, the PSRAM enters into the refresh state during the non-selection state, and is refreshed. This refresh operation is necessarily performed after an access to PSRAM.