A voltage generating circuit includes: a first output voltage generator to receive an input voltage, to output a first output voltage, to compare the input voltage with a first reference voltage, and to stop the output of the first output voltage according to the comparison; and a second output voltage generator to receive the input voltage, to output a second output voltage, to compare the input voltage with a second reference voltage, and to stop the output of the second output voltage according to the comparison. The first output voltage generator is to compare first reference voltage data with second reference voltage data, and to change the first reference voltage according to the comparison. The second output voltage generator is to compare the first reference voltage data with the second reference voltage data, and to change the second reference voltage according to the comparison.