Patent ID: 7724071

Claim:
A semiconductor device comprising: a pump circuit that boosts an output node connected to a memory cell array; an oscillator that outputs a plurality of clocks to the pump circuit, wherein a frequency of the oscillator is set equal to or lower than the frequency at which the efficiency of the pump circuit does not substantially depend on the frequency, with the pump circuit effectively boosting the output node, and wherein the pump circuit comprises a plurality of sub pump circuits; and the oscillator outputs the plurality of clocks having phases shifted from one another to the sub pump circuits; and a detection circuit that outputs an actuating signal to the oscillator, the actuating signal actuating the oscillator when a voltage of the output node of the pump circuit is lower than a first reference voltage, the actuating signal stopping the oscillator when the voltage of the output node is higher than a second reference voltage, and the first reference voltage being different from the second reference voltage; wherein the plurality of clocks stop in different timings such that the plurality of sub pump circuits stop in different timings, and the plurality of clocks are actuated in different timings such that the plurality of sub pumps are not actuated at the same time.