Patent ID: 7944439

Claim:
A display device comprising: a first voltage generation circuit comprising a first voltage circuit for outputting an internal voltage on the basis of a plurality of clocks, a first sampling circuit for sampling an output signal from the first voltage circuit, a first monitoring circuit for comparing an output signal from the first sampling circuit with a predetermined voltage range and outputting a result, and a power supply generation circuit for generating a power supply voltage to be input to the first voltage circuit on the basis of an output signal supplied from the first monitoring circuit; and a second voltage generation circuit comprising a second voltage circuit for outputting an internal voltage on the basis of a plurality of clocks, a second sampling circuit for sampling an output signal from the second voltage circuit, a second monitoring circuit for comparing an output signal from the second sampling circuit with a predetermined voltage range and outputting a result, and a clock generation circuit for generating the clocks to be input to the second voltage circuit on the basis of an output signal supplied from the second monitoring circuit, wherein the first voltage circuit is controlled on the basis of a level of the power supply voltage, and the second voltage circuit is controlled on the basis of periods of the clocks.