Patent ID: 7159132
Filing Date: 2007-01-02
Classification: G06F

Abstract:
1. A USB device for performing communications with a second device through a USB interface while supplying electric power to the second device through a power-source supplying line in the USB interface, the USB device comprising: a communication unit that communicates with the second device; a power source that outputs a voltage selected from a plurality of voltages that include a standard USB interface voltage and a voltage different from a standard USB interface voltage; and a selection unit that selects any one of the plurality of voltages for output by the power source; wherein the power source supplies one of a selected different voltage and a selected standard USB interface voltage through the power-source supplying line, and wherein the selection unit sets the selected voltage to a standard USB interface voltage after it is detected that the connection between the USB device and the second device is disconnected and before it is detected that a connection between the USB device and another device is established.