GENERAL DESCRIPTION

The VSC7177 is a Serial ATA and Serial Attached SCSI multiplier/buffer that implements a 2:1 port selector function for 1.5 Gbps and 3.0 Gbps links. This function is used when dual hosts, such as I/O controllers, must access single-port disk drives in high availability storage subsystems where redundancy and load sharing are important. The outputs from the I/O controllers are muxed to a Serial ATA or Serial Attached SCSI drive. The output from the Serial ATA drive is buffered and replicated to the I/O controllers. When switching from one I/O controller to the other, a Serial ATA link must be re-initialized with out-of-band (OOB) signals, which are transferred through the VSC7177 transparently. The VSC7177 provides high output swings, pre-emphasis, and programmable receiver sensitivity that are needed to drive long backplanes and external cables.

FEATURES

● 2:1 port selector for both Serial ATA (SATA) and Serial Attached SCSI (SAS) links

● Serial ATA 1.0 compliant at 1.5 Gbps (3.0 Gbps capable)

● Sideband port selection

● Complies with Serial ATA II: Port Selector specification 1.0, including failover control

● Passes Serial ATA patterns transparently

● Programmable receiver sensitivity

● High output swing mode with pre-emphasis

● Compatible with legacy designs (VSC7173 and VSC7175); provides enhanced connectivity and signal pre-emphasis

● 0.6 W to 0.8 W power dissipation (depending on operating mode)

● 3.3 V power supply

● 32-pin, 7 mm x 7 mm QFP-N package

APPLICATIONS

● Active-passive redundant failover systems

● Dual-port Serial ATA and Serial Attached SCSI disk arrays (JBODs)

● NAS servers

● RAID subsystems

● Disk-based backup systems

● Serial ATA and Serial Attached SCSI routing applications

● Buffers for externally connected links