| 摘要 |
A USB(Universal Serial Bus) device for sensing USB connection is provided to sense USB connection correctly regardless of influence of a USB cable and an operation state of a USB device. A tri-state buffer(211) receives an input signal corresponding to USB power provided from a pc(101). A first pull-down resistor(212) sets an initial value of the tri-state buffer by connecting to the tri-state buffer. A bi-state buffer(210) is connected to an edge of the tri-state buffer and removes oscillation caused by an undefined area of the tri-state buffer. A USB connection sensing module senses the USB connection from rising and falling edges output from the tri-state buffer. A ripple and discharge processing module removes and discharges ripple from the USB power. An enable pin of the tri-state is connected to a USB pull-up enable port for controlling pull-up operation of a data line transmitting USB data. An SOC(System On Chip)(120) includes an USBPUEN(105) port for performing a pull-up operation and a DM/DP port(113) for transmitting real data.
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