Patent ID: 7185132

Claim:
A USB controller with an intelligent transmission mode switching function, comprising: a data line set including a D+ data line and a D− data line for transmitting data; a monitor unit coupled to said data line set; a host controller coupled to said monitor unit for performing a host mode operation by a USB interface; a device controller coupled to said monitor unit for performing a device mode operation by a USB interface, said monitor unit selectively coupling one of the host controller and the device controller to said data line set responsive to said monitor unit detecting a variation of a potential on the data line set to determine a transmission mode of the USB controller; a power line including a front-end power line and a back-end power line, connected in series by a switch; a pull-up resistor having one end connected to the front-end power line; and an adapter connected to the other end of the pull-up resistor for selectively coupling the pull-up resistor to one of the D+ data line and the D− data line.