The MAX3891 serializer converts 16-bit wide, 155Mbps parallel data to 2.5Gbps serial data in ATM and SDH/SONET applications. The MAX3891 is ideal for interfacing with high-speed digital circuitry. This device accepts single-ended LVPECL data inputs and delivers differential LVPECL data and clock outputs. An internal 2.5Gbps serial clock, synthesized by a fully integrated PLL that accepts multiple input reference clock rates, retimes the output data stream. The MAX3891 operates from a single +3.3V supply and accepts differential LVPECL reference clock rates of 155.52MHz, 77.76MHz, 51.84MHz, or 38.88MHz. A CML loopback data output is provided to facilitate system diagnostic testing. The MAX3891 is available in the extended temperature range (-40C to +85C) in a 64-pin TQFP exposed pad (EP) package.