Patent ID: 8410821
Filing Date: 2013-04-02
Classification: G05F

Abstract:
1. An output current detecting circuit, comprising: an output circuit including an output transistor connected between a power source voltage terminal and an output terminal; a current detecting transistor having a size smaller than a size of the output transistor, and a control terminal, to which a voltage is applied that is the same as a voltage applied to a control terminal of the output transistor, to flow a current according to the size of the current detecting resistor through the current detecting transistor; a first resistance element connected to the current detecting transistor in a serial mode; a comparison circuit for comparing a voltage converted by the first resistance element and a predetermined reference voltage to judge a magnitude of a current flowing through the output transistor; and a reference voltage generating circuit for generating the reference voltage, wherein the reference voltage generating circuit includes a constant current circuit flowing a constant current and a second resistance element having one terminal connected to the power source voltage terminal, the reference voltage generating circuit generating the reference voltage based on a power source voltage at the power source voltage terminal by converting the constant current generated by the constant current circuit into a voltage by flowing the constant current through the second resistance element, and wherein the output current detecting circuit further comprises a first MOS transistor connected between the constant current circuit and the second resistance element, the first MOS transistor having a gate terminal to which a voltage is applied that is the same as the voltage applied to the control terminal of the current detecting transistor.