LU3X54FT

Bused MII Mode The LU3X54FT has been designed for operation in two basic system interface modes of operation:
Normal MII Mode (Four Separate MII Ports). The separate mode provides four independent RJ-45 to MII ports and is similar to having four independent 10/100 transceivers.
 Bused MII Mode. This mode is designed specifically for repeater applications to save pins. In bused mode: - Data from all of the ports operating at 100 Mbits/s will be internally bused to system interface port A
(100 Mbits/s MII interface). - Data from all of the ports operating at 10 Mbits/s will be internally bused to system interface port B (7-pin 10 Mbits/s serial interface). The LU3X54FT will automatically detect the speed of each port (10 Mbits/s or 100 Mbits/s) and route the data to the appropriate port.