Abstract: In a ring oscillator constituting an oscillating circuit, resistor circuits are used as delay circuits to be connected to respective inverters. That is, the inverters and the resistors are connected in series so that the resistor is provided between the adjacent inverters. With the arrangement, it is possible to provide an oscillating circuit which is less dependent on any of power supply voltages, temperatures, and manufacturing variations, while maintaining a characteristic in which the oscillating frequency decreases as an output voltage of a booster circuit increases.

Abstract: An object of the present invention is to provide a nonvolatile semiconductor memory device having a storage region constructed by a plurality of electrically rewritable nonvolatile memory cells and a booster circuit for boosting a power source voltage to thereby generate a voltage necessary to rewrite the storage region, wherein the power source voltage can be prevented from being decreased in the device and data in the storage region can be stably rewritten. The nonvolatile semiconductor memory device has a voltage determining part for determining a voltage level of a predetermined node in the semiconductor memory device in rewriting of the storage region, and a rewrite unit determining part for determining the number of bits of input data to be rewritten at once on the basis of a result of determination of the voltage determining part.

Abstract: In a ring oscillator constituting an oscillating circuit, resistor circuits are used as delay circuits to be connected to respective inverters. That is, the inverters and the resistors are connected in series so that the resistor is provided between the adjacent inverters. With the arrangement, it is possible to provide an oscillating circuit which is less dependent on any of power supply voltages, temperatures, and manufacturing variations, while maintaining a characteristic in which the oscillating frequency decreases as an output voltage of a booster circuit increases.

Abstract: An object of the present invention is to provide a nonvolatile semiconductor memory device having a storage region constructed by a plurality of electrically rewritable nonvolatile memory cells and a booster circuit for boosting a power source voltage to thereby generate a voltage necessary to rewrite the storage region, wherein the power source voltage can be prevented from being decreased in the device and data in the storage region can be stably rewritten. The nonvolatile semiconductor memory device has a voltage determining part for determining a voltage level of a predetermined node in the semiconductor memory device in rewriting of the storage region, and a rewrite unit determining part for determining the number of bits of input data to be rewritten at once on the basis of a result of determination of the voltage determining part.

Abstract: A method for inspecting a semiconductor memory device by using an inspection microcomputer and a memory for storing a test program for the inspection. The semiconductor memory device includes a non-volatile memory area, a peripheral circuit thereof, a control circuit for controlling writing and erasing of data to and from the non-volatile memory area via the peripheral circuit, and a control bus for connecting the control circuit and the peripheral circuit. The method includes the steps of: deactivating the control circuit; connecting the inspection microcomputer and the memory to the control bus; and inspecting the peripheral circuit and the non-volatile memory area by the inspection microcomputer.