Semiconductor integrated circuit having a function determination circuit

摘要

DC voltage V_REF produced in an LSI and having a value between power supply voltage V_DD and the ground potential is applied to the gate electrode of pMOS transistor Q_P1 which forms a function determination circuit. Since the gate voltage of a transistor Q_P1 is lower than that in a conventional function determination circuit, current through the transistor Q_P1 is reduced. Hence, the gate length of the transistor Q_P1 can be reduced. When a second pMOS transistor is connected in parallel to the transistor Q_P1 so that the transistor has a function for supplying charge to junction A when power is fed to the LSI, the area of the transistor Q_P1 can be further reduced. When a voltage produced for a purpose other than for the function determination circuit such as a step-down power supply of the LSI is used as DC voltage, the area of the transistor can be reduced.