Patent ID: 7535267

Claim:
An output circuit comprising: an output transistor connected to a load and used as a current source connected between a power supply line and an output terminal for the load; a current detection circuit for detecting a current flowing through the output transistor, wherein the current detection circuit includes a detection transistor connected in parallel to the output transistor to supply a detection current proportional to a current flowing through the output transistor; and a driving circuit for supplying a base current, which is determined in accordance with the detection current supplied by the current detection circuit, to the output transistor, wherein the current detection circuit and the driving circuit are connected to form a feedback loop to increase the base current of the output transistor as the current detected increases, wherein: the detection transistor has an emitter connected to an emitter of the output transistor and a base connected to a base of the output transistor; and the driving circuit includes a current mirror circuit connected to the detection transistor and the output transistor for receiving the detection current, which flows to the detection transistor, as an input, and supplying the base current to the base of the output transistor at a same level as the detection current; and a diode having a cathode connected to the output transistor and an anode connected to the current mirror circuit of the driving circuit, wherein the cathode is not directly connected to a collector of the detection transistor.