Patent ID: 7424569

Claim:
A data transfer control device for transferring data through a USB, comprising: a transfer controller that controls a data transfer; and a power supply switching circuit that controls a switching of supplying power to a VBUS line of the USB, when the data transfer control device is a first data transfer control device connected to a type-A plug side of the USB and supplies power to the VBUS line, the transfer controller transmits a switching request packet of supplying power to a second data transfer control device connected to a type-B plug side of the USB, the switching request packet of supplying power containing a request to switch the supplying of power to the VBUS line to the second data transfer control device; and if the transfer controller receives a switching acknowledgment packet of supplying power from the second data transfer control device connected to the type-B plug side, then the transfer controller instructs the power supply switching circuit to stop supplying power to the VBUS line, wherein the supplying of the power to the VBUS line is switched from the first data transfer control device connected to the type-A plug side of the USB to the second data transfer control device connected to the type-B plug side of the USB.