The 853S54I is a dual 2:1 and 1:2 Multiplexer. The 2:1 Multiplexer allows one of 2 inputs to be selected onto one output pin and the 1:2 MUX switches one input to one of two outputs. This device is useful for multiplexing multi-rate Ethernet PHYs which have 100 M bit and 1000 bit transmit/receive pairs onto an optical SFP module which has a single transmit/receive pair. See Application Section for further information. The 853S54I is optimized for applications requiring very high performance and has a maximum operating frequency of 2.5GHz. The device is packaged in a small, 3mm x 3mm VFQFN package, making it ideal for use on space-constrained boards.