Abstract: In order to optimize writing of the cell, the latter is written in a condition of equilibrium between an injection current Ig and the displacement current CppVsl. In this way, during writing, the voltage of the floating gate region Vfl remains constant, as does the drain current and the rise in the threshold voltage. In particular, both for programming and for soft-writing after erasure, the substrate of the cell is biased at a negative voltage Vsb with respect to the source region, and the control gate region of the cell receives a ramp voltage Vcg with a selected predetermined inclination Vsl satisfying an equilibrium condition Vsl<Ig,sat/Cpp.