XRS10L220

The XRS10L220 provides the combined advantages of the Serial ATA II Port Selector and Port Multiplier implementations for Serial ATA II systems at 3.0 Gbps and 1.5 Gbps. Combining the capability to address two Serial ATA devices from one external link with support for a failover path from two independent hosts, the XRS10L220 offers a leading solution for propagation of high data rate Serial ATA products in a wide variety of applications. The integration of Serial ATA PHY links, a variety of digital logic capabilities, rate adjust FIFOs, integrated low-cost clock oscillator support, test and loopback features is achieved in a low cost and lower power implementation.

The port selector 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 drive through the port selector block of the XRS10L220. Active/passive port selector in XRS10L220 allows two different host ports to connect to the same target in order to create a redundant path to that target. In combination with RAID, the XRS10L220 allows system providers to build fully redundant solutions. This avoids the presence of a single point of failure, and enables a fail-over path in the case of host failure.

This port multiplier function is used when one active host has to communicate with multiple SATA drives. The XRS10L220 supports up to 2 SATA drives and utilizes the full bandwidth of the host connection.

The XRS10L220 includes enhanced features such as staggered HDD spin-up, power management control, hot plug capability and support for legacy software. The XRS10L220 acts as a retimer, maintaining independent signaling domains between the drives, hosts and the external interconnect.

The high-speed serial input features selectable equalization adjustment and the high-speed serial output features selectable pre-emphasis to compensate for ISI (Inter-Symbol Interference) and increase maximum cable distances.

XRS10L220 meets tight jitter budgets in SATA applications. Exar's serial I/O technology enables reliable data transmission over 1 meter of FR-4 and 2 meters of unequalized copper cable.

Host and drive port speeds can be mixed and matched, based upon inherent data rate negotiation present in the SATA II specifications.

The MDIO bus allows simple configuration of the XRS10L220.

To summarize, the port multiplier functionality in the XRS10L220 allows the system designer to increase the number of serial ATA connections in an enclosure that does not have a sufficient number of serial ATA connections for all of the drives in the enclosure. The port selector functionality in the XRS10L220 allows replacement for expensive Fibre Channel drives with cost effective and high capacity SATA drives in enterprise class applications without compromising on redundancy or performance.

Standards Compliance

The XRS10L220 is compliant with the following industry specifications:

• Serial ATA, Revision 1.0a
• Serial ATA II: Extensions to Serial ATA 1.0a, Revision 1.2
• Serial ATA II PHY Electrical Specifications, Revision 1.0
• Serial ATA II: Port Selector, Revision 1.0
• Serial ATA II: Port Multiplier, Revision 1.2
• Serial ATA II: Revision 2.6