FemtoClock SAS/SATA Clock Generator

The 843241 is a low jitter, high performance clock generator and a member of the FemtoClock® family of silicon timing products. The 843241 is designed for use in the SAS-2 interconnect and the three transport protocols that use the SAS-2 interconnect: Serial SCSI Protocol (SSP), Serial ATA Tunneled Protocol (STP), and Serial Management Protocol (SMP). The 843241 has excellent (<1ps) RMS phase jitter, over the SAS defined integration range. The 843241 uses an external, 25MHz, parallel resonant crystal to generate three selectable output frequencies: 75MHz, 100MHz, 150MHz, and 300MHz. This silicon based approach provides excellent frequency stability and reliability. The 843241 features up, down, and center spread spectrum (SSC) clocking techniques. The up, down and center SSC will be required in the SAS-2 applications that have three clock trees in the HBA and expander ASICs (see Applications Information section, Figure 3).