The HDMP-1687 is a four channel SERDES device. HDMP-1687 is in a 208-ball TBGA package with four 1.0625/1.25 Gbps serial I/O. This integrated circuit provides a lowcost, low-power, small-form-factor physical-layer solution for multi-link Gigabit Ethernet/Fibre Channel interfaces. This IC may be used to directly drive copper cables, or it may be used to interface with optical transceivers. Each IC contains transmit and receive channel circuitry for all four channels. The transmitter section accepts 10-bit-wide parallel TTL data on each channel and serializes it into a high-speed serial stream. The parallel data is expected to be 8B/10B encoded (or equivalent). Four banks of parallel data are latched into the input registers of the transmitter sections on the rising edge of RFCT. Receive data are latched out with separate clock pins for each channel. These pins may be single 106.25/125 MHz TTL clock outputs RC [0:3] [1] or dual 53.125/62.5 MHz TTL pairs RC [0:3] [0:1] to serve legacy applications where