Patent ID: 8352640

Claim:
A method of controlling a USB dual interface of an electric circuit, the method comprising: receiving a first power supply voltage or a second power supply voltage from a host; generating a reference voltage when either the first power supply voltage or the second power supply voltage is received; detecting the first power supply voltage with reference to the reference voltage, or the second power supply voltage with reference to the reference voltage; transmitting and receiving a first data signal through a first data path and a third data signal through a third data path in response to a signal generated when the first power supply voltage is detected; and transmitting and receiving a second data signal through a second data path and a fourth data signal through a fourth data path in response to a signal generated when the second power supply voltage is detected, wherein transmitting and receiving the first and third data signals comprises communicating the first data signal between a first transceiver and a first switch and communicating the third data signal between a third transceiver and a second switch, and wherein transmitting and receiving the second and fourth data signals comprises communicating the second data signal between a second transceiver and the first switch and communicating the fourth data signal between a fourth transceiver and the second switch.