| 摘要 |
A charge pump circuit 203 boosts a power supply voltage to generate a high voltage VPP in response to clocks CK, CK/ supplied from an oscillation circuit 202. A voltage detecting circuit 205 discriminates whether the high voltage VPP reaches a desired voltage value or not and represents it by discrimination signals LVPP, DIS/. If the high voltage VPP does not reach the desired voltage value, a writing control circuit 201 stops the oscillation circuit 202 from effecting its oscillating operation and stops the charge pump circuit 203 from boosting the power supply voltage to the high voltage VPP in response to the discrimination signal DIS/. Accordingly, the high voltage VPP having a desired voltage value is not applied to a memory cell of a memory circuit 204 so that writing is not effected. Further, the discrimination signal LVPP, is outputted externally so as to represent the writing state in the memory cell.
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