The LXT974 and LXT975 are four-port PHY Fast Ethernet Transceivers which support IEEE 802.3 physical layer applications at both 10 Mbps and 100 Mbps. They provide all of the active circuitry to interface four 802.3 Media Independent Interface (MII) compliant controllers to 10BASE-T and/or 100BASE-TX media. This data sheet applies to all versions of the LXT974 and LXT975 products including LXT974A, LXT974B, LXT975A, and LXT975B. As a result of product changes, Revision 4 parts are labeled LXT974B and LXT975B. Revision 3 parts are labeled LXT974A and LXT975A. The differences in these product revisions are described in the LXT974/975 Specification Update.