A buck converter configured for converting a voltage output from a power supply to a load includes a first switch, a second switch, an inductor, three compensators and a control microchip. The first switch and the second switch are connected in series between two ends of the power supply. A first end of the inductor is connected to a node between the first switch and the second switch; a second end of the inductor serves as an output terminal connected to the load. The compensators are correspondingly connected to the first switch, the second switch and the inductor. The control microchip is electrically connected to the first and second switches and the node. The control microchip controls the first and second switches to turn on or off, and executes a current protective process when output current of the output terminal exceeds a current protective threshold of the load.