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:
Jan. 10, 1995
Filed:
May. 02, 1994
Koichi Kawauchi, Hyogo, JP;
Seiichiro Asari, Hyogo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A nonvolatile semiconductor memory device includes rewritable areas (M10, M20). A control circuit (110) controls a boosting circuit (2) and a writing circuit (10) such that a high voltage is generated from the boosting circuit, and data is written to the rewritable area designated by an address register/decoder (104) by means of the writing circuit. In response to an external signal which is at the 'H' level, the control circuit allows writing of data to the rewritable areas (M10, M20) by means of the writing circuit (9). In response to an external signal which is at the 'L' level, the control circuit prohibits rewriting of data in the rewritable area (M10), and allows rewriting of data in the rewritable area (M20). Therefore, even if the operation mode is erroneously set to the write mode because of unstable state of the power supply, data in the rewritable area is not destroyed.