Circuit for supplying constant voltage

摘要

A constant voltage supplying circuit including an output transistor is connected to a power source line and an output terminal. A base-emitter voltage of the output transistor is detected by a voltage detecting circuit composed of a transistor. A current-outputting circuit for supplying a current determined based on the voltage detected by the voltage detector to a reference voltage supplying circuit is used in the constant voltage supplying circuit. The reference voltage is supplied to a base of the output transistor to cancel a base-emitter voltage of the output transistor and to equalize the output voltage to a voltage generated in a reference voltage generating element included in the reference voltage supplying circuit. In this manner, the output voltage is kept constant notwithstanding variation of output current.