| 摘要 |
<p>PURPOSE:To easily prevent a stored data from being destroyed by providing a floating gate type MOS for detecting the decrease of charge at the specified bit of the ultraviolet erase EPROM composed of the floating gate type MOS. CONSTITUTION:A floating gate type MOS 3 is provided for detecting the decrease of charge. This floating gate type MOS 3 for detecting the decrease of charge is one part of floating gate type MOS 3 of multiple bits constituting the ultraviolet erase EPROM. When the EPROM is reloaded, the charge is simultaneously injected to the floating gate, and a second reading voltage to the gate is made close to a threshold voltage rather than the first reading voltage of the floating gate type MOS 2 of multiple bits. Therefore, since the data of the floating gate type MOS 3 for detecting the decrease of charge is inverted before inverting a data stored in the floating gate type MOS 2 of multiple bits, this inversion is detected and the stored data is reloaded. Thus, the stored data can be easily prevented from being destroyed.</p> |
