Switch control circuit, switch control method, and power supply device using the same

The present invention relates to a switch control circuit, a switch control method, and a power supply device using the same. The power supply device supplies power to a load by using an input voltage. A switch control circuit controls the switching operation of a power switch which controls the power supply device. The switching control circuit detects the duty of the power switch by using a signal for controlling the switching operation of the power switch, detects the load by using a feedback voltage, and determines whether or not the short circuit of detection resistance exists according to the duty and detected load.