Abstract: A semiconductor integrated circuit includes a first power system element group having an internal circuit for providing an output signal, and a second power system element group for receiving the output signal. An independently activated and deactivated power source potential is supplied to each of the first and second power system groups. In one embodiment of the invention, a fixing circuit maintains the level of the output signal from the internal circuit when the power source input potential to the first group is lowered or turned off. As a result, through currents in the nature of transitional large currents are reduced in the internal circuit elements of the second group.

Abstract: A nonvolatile semiconductor storage device has a sense characteristic modifying circuit for modifying the sense characteristic of a sense amplifier that amplifies the data in a memory cell and a volatilization discriminating unit that discriminates whether or not a memory cell suffers volatilization by comparing the level of a data read before modifying the sense characteristic and the level of a data read after modifying the sense characteristic. In this nonvolatile semiconductor storage device, the level of the data read on the basis of a sense characteristic with a more strict criterion is compared with the level of the data read on the basis of another sense characteristic with a less strict criterion, and it is discriminated whether or not the memory cell suffers volatilization on the basis of the result of the comparison.