Series regulator having a power supply circuit allowing low voltage operation

Abstract

There is disclosed a semiconductor device, which allows the ripple rejection characteristics to be improved and the operating voltage to be reduced. The semiconductor device comprises a power supply circuit arranged between an input terminal and internal circuits so as to make a connection therebetween, said power supply circuit including a transistor Q for supplying each of the internal circuits with a drive voltage and another transistor Q for allowing a current to pass therethrough in response to a magnitude of a reference voltage supplied to a base thereof and a magnitude of the drive voltage supplied to an emitter thereof. A part of the circuit composed of transistors Q , Q and a resistor R controls a current flowing through of the transistor Q based on the current that has passed though the transistor Q , so that the drive voltage could be set to a value higher than the reference voltage approximately by a magnitude of a forward voltage between the base and the emitter of the transistor Q .