In response to the demand of high-speed USB market, USB2.0 has been introduced and widely applied to various devices for its high-speed attachment capacity, plug-and-play and hot plugging functionalities that help to improve user experience and device ease of use. According to the USB2.0 Specification, high-speed (HS) and full-speed (FS) interfaces support data transfer rate of up to 480 Mbps and 12 Mbps, respectively. The USB OTG, as USB2.0 standard supplementary interface, is able to act as a device or host to support externally connected USB flash disk to read file content or expand functions with external devices, such as mouse, headphone and keyboard.