The KSZ8051 is a single supply 10Base-T/100Base-TX Ethernet physical layer transceiver for transmission and reception of data over standard CAT-5 unshielded twisted pair (UTP) cable. The KSZ8051 is a highly integrated, compact solution. It reduces board cost and simplifies board layout by using on-chip termination resistors for the differential pairs and by integrating a low noise regulator to supply the 1.2V core. The KSZ8051MNL offers the Media Independent Interface (MII) and the KSZ8051RNL offers the Reduced Media Independent Interface (RMII) for direct connection with MII/ RMII compliant Ethernet MAC processors and switches. A 25MHz crystal is used to generate all required clocks, including the 50MHz RMII reference clock output for the KSZ8051RNL. The KSZ8051 provides diagnostic features to facilitate system bring-up and debugging in production testing and in product deployment. Parametric NAND tree support enables fault detection between KSZ8051 I/Os and board. Micrel LinkMD® TDR-based cable diagnostics permit identification of faulty copper cabling.