Peripheral interface chip and data transmission method thereof

A peripheral interface chip, comprising:

• a switching circuit, coupled to a universal serial bus (USB) device through a first USB interface and coupled to a controller hub through a second USB interface;
• a USB host controller, coupled to the switching circuit;
• a keyboard controller, coupled to the controller hub through a low pin count (LPC) interface;
• and
• a microprocessor, coupled to the USB host controller and the keyboard controller,
• wherein the switching circuit receives a device identification transmitted from the USB device, the device identification is used for determining whether the USB device is a keyboard device, and when the USB device is the keyboard device, the input data of the USB device is transmitted to the controller hub through the first USB interface, the switching circuit, the USB host controller, the microprocessor, the keyboard controller and the LPC interface.