The KSZ8081RNACA TR 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. This is a highly-integrated PHY 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 and by offering 1.8/2.5/3.3V digital I/O interface support. It offers the reduced media independent interface (RMII) for direct connection to RMII-compliant MACs in Ethernet processors and switches. As the power-up default, this uses a 25MHz crystal to generate all required clocks, including the 50MHz RMII reference clock output for the MAC. This version takes in the 50MHz RMII reference clock as the power-up default.