The S2042 and S2043 transmitter and receiver pair are designed to perform high-speed serial data transmission over fiber optic or coaxial cable interfaces conforming to the requirements of the ANSI X3T11 Fibre Channel specification. The chipset is selectable to 1062, 531 or 266 Mbit/s data rates with associated 10- or 20-bit data word. The chipset performs parallel-to-serial and serial-toparallel conversion and framing for block-encoded data. The S2042 on-chip PLL synthesizes the highspeed clock from a low-speed reference. The S2043 on-chip PLL synchronizes directly to incoming digital signals to receive the data stream. The transmitter and receiver each support differential PECL-compatible I/O for fiber optic component interfaces, to minimize crosstalk and maximize data integrity. Local loopback allows for system diagnostics. The TTL I/O section can operate from either a +3.3V or a +5V power supply. With a 3.3V power supply the chipset dissipates only 1W typically.