Patent ID: 8539266

Claim:
A USB electronic device with a power source loaded therein, which is connected to another USB electronic device via a USB connector, comprising: a voltage detection unit that detects a voltage at an identification line corresponding to an identification pin of the USB connector; a power supply control unit that controls connection/disconnection between a power supply pin of the USB connector and the power source based upon a voltage change at the identification line detected by the voltage detection unit; and an allow/disallow control unit that executes control to allow/disallow detection of a voltage change at the identification line, wherein: the power supply control unit includes: a first switch disposed between the power supply pin and the power source, with which the power supply pin and the power source are connected with each other or disconnected from each other in response to a switching control signal; and a second switch with which allow/disallow control is executed with regard to changeover at the first switch based upon the voltage at the identification line detected by the voltage detection unit, wherein: when the changeover at the first switch is allowed via the second switch, the switching control signal is applied to the first switch via the second switch, and when the changeover at the first switch is disallowed via the second switch, the switching control signal is interrupted from the first switch by the second switch, and the second switch is disposed between a switching control terminal of the first switch and the identification line so as to connect/disconnect the switching control terminal of the first switch to/from the identification line; and the allow/disallow control unit includes: a pull-up circuit; and a switch that connects/disconnects the power source to the identification line via the pull-up circuit, wherein the switch connects the power source to the identification line when the detection of the voltage change is allowed and disconnects the power source from the identification line when detection of the voltage change is disallowed.