| 摘要 |
<p>PURPOSE:To enhance the reliability of a memory element by a method wherein an erasure and write time circuit and an erasure and write voltage generation circuit are controlled by means of an output signal from a set condition storage area in a memory device. CONSTITUTION:When a nonvolatile memory is erased, a memory erasure signal 11 is input to a timer circuit 13. An erasure pulse-width setting signal 15 and an erasure voltage-value setting signal are read out from a set condition storage area 45 in a memory chip 41; they are input respectively to an erasure pulse-width setting circuit 14 and an erasure voltage-value setting circuit 20. A circuit 19 receives a pulse signal having a width T1 from the circuit 13; it outputs an output signal 23 having the width T1 and a voltage value VPP1; it performs an erasure operation. On the other hand, in a write operation, a write signal 25 is input to a write timer circuit 27. A write pulse-width setting signal 29 and a write voltage-value setting signal 35 are read out form the area 45; they are input respectively to the circuit 27 and a circuit 33. The write voltage generation circuit 33 receives a pulse signal having a width T2 from the circuit 27; it outputs an output signal having the width T2 and a voltage value VPP2; it performs a write operation.</p> |
