| 摘要 |
When an input voltage determining circuit 24 determines that an input voltage exceeds a prescribed voltage, a control circuit 25 of a positive polarity power selector circuit 22 turns on a first switch SW 1 and turns off second and third switches SW 2 and SW 3 , thereby supplying the input voltage to a memory cell array 21 via the first switch SW 1 . When the input voltage determining circuit 24 determines that the input voltage is not higher than the prescribed voltage, the control circuit 25 turns off the first switch SW 1 and turns on the second and third switches SW 2 and SW 3 , thereby supplying a voltage from a charge pump 23 via the second and third switches SW 2 and SW 3 . By this operation, the memory element is able to retain storage of two bits or more even if miniaturized, to execute stable operation with a small circuit area and to prevent circuit malfunction attributed to a small current supplied to the memory cell array.
|
