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:
May. 11, 2004
Filed:
Jan. 22, 2002
Yasuaki Hirano, Tenri, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
In a nonvolatile semiconductor memory device, a voltage Vpp of 12 V applied to an external terminal is dropped by a resistance element of 3500 &OHgr; to a voltage Vrpin. Vrpin is inputted to a regulator circuit to output a stabilized voltage Vpll of 5 V, so that Vpll is applied to a common source line as an erase pulse voltage. Termination of a first erase pulse application is judged by a level detection circuit based on a result of comparison between a reference voltage Vref of 11 V and an input voltage Vrpin which begins with 5 V upon start of the erase operation. Thus, since a large voltage magnitude of the input voltage is secured, a variation in the threshold voltage of a memory cell after the termination of the first erase pulse application can be made small, thereby preventing degradation of the erase speed.