A power supply circuit configured to generate an output voltage from a predetermined AC voltage. The power supply circuit includes a rectifier circuit rectifying the predetermined AC voltage, an inductor receiving a rectified voltage from the rectifier circuit, a transistor controlling an inductor current flowing through the inductor, and an integrated circuit configured to drive the transistor based on the inductor current and the output voltage. The integrated circuit includes a comparison circuit configured to compare a current value of the inductor current and a predetermined current value, and a timer circuit configured to receive a comparison result indicating that the current value is smaller than the predetermined current value, and output a signal indicating that the AC voltage is interrupted, when the current value has been smaller than the predetermined current value for a predetermined time period.