Importance

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Abstract

A USB connection-detection circuitry and the operation method of the same are disclosed. The circuitry includes a transmitting circuit and a detecting circuit. The transmitting circuit contains a pair of differential signal lines, a pair of pull-down resistors and a pair of pull-up resistors wherein one pull-down resistor and one pull-up resistor are connected to the same differential signal line with their own individual switches. A power-related signal supplied by a power-supply system is received by the transmitting circuitry and transmitted through a differential signal line. Then, the power-related signal is grounded via a pull-down resistor. The detecting circuit is utilized to detect the power-related signals, which flow through the differential 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 with the differential signal lines of this circuitry. This results in the variation of the power-related signals, which are connected to the ground through the pull-down resistors originally. Therefore, by comparing the difference of 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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First Claim