| 摘要 |
PURPOSE: A power supply circuit of a USB hub is provided to select not only a bus power being inputted through an upstream cable but a self-power being generated in a local power unit, if necessary, by connecting to a necessary cable without operating an additional switch. CONSTITUTION: In a USB power unit(420) of a USB hub(400) which receives a power source through one out of an upstream cable and a local power unit(300) and uses the power source for an internal power consumption of the USB hub(400) and for a power source being distributed to other USB device through each downstream port, a local power unit(300) is mounted in a USB power unit(420) and receives a self-power. A power interface unit(421) is located at the front end of the local power unit(300). In the case that a self-power is not inputted from the local power unit(300), the power interface unit(421) receives a bus power through the upstream cable, and supplies a bus power to the USB hub(400) and the downstream port. In the case that a self-power is inputted from the local power unit(300), the power interface unit(421) blocks the bus power by the self-power and supplies the self-power to the USB hub(400) and the downstream port.
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