| 摘要 |
<p>PURPOSE:To prevent the write defect of a memory cell by providing a source bias circuit, which increases a source potential while detecting the leak current of a drain at the write time of a non-volatile memory, and an Unerasable Programmable ROM (UPROM), which can not be erased by ultraviolet rays, to set whether this source bias circuit can be used or not. CONSTITUTION:The source bias circuit 10 is provided to increase the source potential while detecting the leak current of the drain at the write time of non-volatile memories M -M, and the UPROM 3, which can not be erased by the ultraviolet rays, is provided to set whether this source bias circuit 10 can be used or not. Therefore, when the UPROM 3 sets the use of the source bias circuit and the leak current of the drain is detected at the write time, an electric field between the drain and the source of the memory cell is relaxed by increas ing the source potential rather than a GND level. Thus, the leak current of the drain is eliminated and the write defect caused by drain potential drop can be canceled.</p> |
