| 摘要 |
PROBLEM TO BE SOLVED: To provide a USB connection-detection circuitry that can automatically recognize the mode of a connected device, and to provide an operation method of the same. SOLUTION: The USB connection-detection circuitry includes a transmission circuit and a detection circuit. The transmit circuit is utilized for receiving power-related signals from a power supply system. Each power-related signal is connected to ground via a pull-down resistor. The detecting circuit is utilized to detect a variation in the power-related signals which flow via differential signal lines. When a device is connected to this connection-detection circuitry with a USB cable, the differential signal lines of the USB cable are connected to the differential signal lines of this circuitry. Since this causes variation of the power-related signals, which originally flow through pull-up resistor elements, by comparing the difference in the power-related signals, before and after the connection, the connection-detection circuitry is able to automatically identify the mode of the device, which connects to the circuitry.
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