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

Part Number	Status
VSC7177	Active: In Production. But some versions of the family are Not Recommended for New Designs. See Ordering Information.

The VSC7177 is a Serial ATA and Serial Attached SCSI multiplier/buffer that implements a 2:1 port selector function for 1.5Gbps and 3.0Gbps 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, preemphasis, 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 of the full data sheet.

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