Patent ID: 8531163

Claim:
A switching power supply device having an input power supply and a load, comprising: a switching element disposed between the input power supply and the load; an inductive circuit coupled to the input power supply, supplying a current to the switching element; a power supply control integrated circuit for controlling the switching element to apply a constant output voltage to the load, the power supply control integrated circuit including a control circuit that controls operations of the power supply control integrated circuit, a drive circuit that, under the control of the control circuit, drives to turn on or off the switching element, a condition setting circuit that, under the control of the control circuit, determines an operation condition of the switching power supply device, and outputs a condition indicating signal indicating the operation condition, a control signal output terminal for outputting a drive signal to the switching element, and a current signal input terminal for inputting a sense current signal to the power supply control integrated circuit; and a resistor of an adjustable resistance connected to the control signal output terminal, or to the current signal input terminal, wherein the condition setting circuit injects a current from the control signal output terminal or from the current signal input terminal into the resistor, detects a voltage generated at the control signal output terminal, and determines the condition indicating signal using the detected voltage.