VSC7177 Data Sheet

Enhanced 2:1 Port Selector for Serial ATA and Serial Attached SCSI

Revision 4.2

July 29, 2005

Confidential

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

Maxim Integrated Products

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To order the VSC7177 device, see “Ordering Information,” page 24.

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.

Port connectivity for the device can be configured using driving external I/O pins or through protocol-based port. See

the block diagram on page 2.

Serial Attached SCSI (SAS) links

(3.0 Gbps capable)

specification 1.0, including failover control

VSC7175); provides enhanced connectivity and

signal pre-emphasis

operating mode)

disk arrays (JBODs)

applications