Memory having charge-carrying floating gate memory cells with

Abstract

A non-volatile memory device provided with a memory cell having a charge storage layer with a threshold voltage which changes in accordance with an amount of charge stored wherein one value from a plurality of possibles values is written into the memory cell, comprising an auxiliary internal power source; a means for adjusting an amount of charges stored by the charge storage layer in accordance with a state of application of the voltage; a time counting means for counting a time elapsed from when a final write operation is carried out with respect to the memory cell; and a refreshing means for comparing the time counted by the counting means and a preliminarily set charge holding time limit, supplying the voltage of the auxiliary internal power source to the memory cell when the counted time reaches the charge holding time limit, and performing a repeat write operation.