| 摘要 |
<p>PURPOSE:To detect abnormality of a threshold voltage by providing a means to supply a first gate voltage internally generated to obtain corresponding read data, and a means to obtain a read data corresponding to a second gate voltage supplied externally. CONSTITUTION:After the end of writing, if a reading is normally executed by means of a specific voltage VS generated by a gate voltage setting part 103, the low threshold voltage VTW of a storing use TR 109 is lower than the VS. Then, a voltage in a value lower than the VS by a marginal value alpha is supplied to a terminal Vcg to execute reading. And, if the reading is normal, the VTW is understood to have a margin of the value alpha or more. Accordingly, by attaining a supply voltage whose output terminal OUT is in L-level, the value of the VTW can be measured. After the end of an erasing action, a reading action is executed by supplying a voltage higher than the terminal Vcg by a marginal value beta. If the erasing action is normal, a high threshold VTE is understood to have a margin of beta or more. This operation is repeated, and the value of the VTE can be measured by attaining a supply voltage whose output terminal OUT is in H-level.</p> |
