Functional Description
This data sheet describes HDMP-1685A, a 1.25 Gbps, four-channel, 5-pin per channel parallel interface SERDES device. The HDMP-1685A 5-pin parallel interface device enables a single ASIC to drive twice as many channels using half as many parallel lines. This is accomplished without increasing the clock frequency by utilizing the bandwidth on the parallel interface more efficiently.

Features
• 5-bit wide Tx, Rx bus pairs
• 208-ball, 23 mm TBGA package
• Parallel data I/O and clocks compatible with SSTL_2 (EIA/JESD8-9)
• 125 MHz TC, RC clocks
• One TC clock for 4 channels
• Single or paired RC clocks
• LVTTL RefClk input
• Source synchronous clocking of transmit data
• Source centered clocking of receive data
• Double data rate (DDR) parallel transfers
• Parallel loopback
• Differential BLL serial I/O
• Single +3.3 V power supply
• Copper drive capability

Applications
• High density fast ports
• Fast serial backplanes
• Clusters of computers
• Clusters of network units
• Link aggregation, trunks