| 摘要 |
An identification circuit is connected between a universal serial bus (USB) interface, and each of a controller and a power management unit (PMU). The identification circuit includes first to fourth electronic switches. When a power adapter is connected to the USB interface, the negative data pin of the USB interface is floating. The first and fourth electronic switches are turned off. The second and third electronic switches are turned on. Power from the power adapter is transmitted to the second power pin of the PMU. When the USB interface is connected to a computer, the negative data pin of the USB interface outputs a low level signal. The first and fourth electronic switches are turned on. The second and third electronic switches are turned off. Power from the computer is transmitted to an electronic device with the USB interface.
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