Patent ID: 6710584
Filing Date: 2004-03-23
Classification: G05F

Abstract:
A series regulator comprising:a power transistor connected in series between an input terminal to which a non-stabilized voltage is applied and an output terminal; an amplifier for changing an internal resistance of the power transistor based on a comparison between an output voltage of the power transistor and a reference voltage, and outputting a stabilized constant voltage to the output terminal; a first bias current circuit for generating a bias current to be supplied to a reference voltage circuit that generates the reference voltage, based on the non-stabilized voltage applied to the input terminal; a voltage dividing circuit for generating a divided voltage from the output voltage of the power transistor; an output voltage detecting circuit including a first transistor having a control terminal to which is applied a conversion voltage corresponding to the bias current that the first bias current circuit supplies to the reference voltage circuit; and a second transistor having a control terminal to which is applied the divided voltage, wherein the second transistor is turned on and the first transistor is turned off when the divided voltage has reached the conversion voltage; a second bias current circuit for generating a bias current to be supplied to the reference voltage circuit in response to on-operation of the second transistor, based on the output voltage of the power transistor; and a bias switching circuit for stopping bias-current supply by the first bias current circuit in response to starting of operation of the second bias current circuit.