To solve such a problem that if a reference time constant generation circuit is provided outside an integrated circuit, the number of terminals of the integrated circuit increases and the area of a semiconductor chip increases, and as a result, the manufacturing cost increases, and a time constant cannot be adjusted by the integrated circuit alone.

By using a switched capacitor, a sufficient precision is maintained even if the time constant generation circuit is incorporated in the integrated circuit. Moreover, by providing a storage section which stores the result of correction of the time constant, a time constant adjustment circuit and a normal operation circuit after the adjustment of the time constant, can partially share each other. The number of terminals of the integrated circuit and the semiconductor chip area are saved on. As a result, the manufacturing cost is reduced. If power is supplied from the outside, the time constant is adjusted automatically and autonomously.