VSC7177

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

The VSC7177 is a Serial ATA and Serial Attached SCSI multiplexer/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 multiplexed 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.