Patent ID: 8313034

Claim:
A semiconductor device comprising: a reference voltage generating circuit including a first reference voltage generating circuit, a second reference voltage generating circuit, and an output switch for switching between an output of the first reference voltage generating circuit and an output of the second reference voltage generating circuit, wherein the output switch switches between an output of the second reference voltage generating circuit and an output of the first reference voltage generating circuit in accordance with an input switch signal, wherein the second reference voltage generating circuit is a threshold-difference-using-type reference voltage generating circuit which uses the difference between two kinds of thresholds of metal oxide semiconductor (MOS-FET), a comparator for detecting a potential difference between an output of the threshold-difference-using-type reference voltage generating circuit and a reference potential in a band gap reference of a band gap reference circuit; and a transistor, wherein when the reference potential in the band gap reference is smaller than the output of the threshold-difference-using-type reference voltage generating circuit, current flows in the transistor to increase the reference potential in the band gap reference.