SERIAL ATA II: 1:4 PORT MULTIPLIER
The EXAR XRS10L140 is a Serial ATA port multiplier
designed for next generation enterprise class disk
array systems that use SATA mid-planes. The device
is targeted at low cost storage applications.
This function is used when one active host has to
communicate with multiple SATA drives. The
XRS10L140 supports up to 4 SATA drives and utilizes
the full bandwidth of the host connection.
The upstream ports of XRS10L140 can also be
attached to a port selector (XRS10L20) or a Serial
ATA Switch to provide redundancy in a more complex
The XRS10L140 includes enhanced features such as
staggered HDD spin-up, power management control,
hot plug capability and support for legacy software.
The XRS10L140 acts as a retimer, maintaining
independent signaling domains between the drives
themselves 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.
XRS10L140 meets tight jitter budgets in SATA
applications. Exar's serial I/O technology enables
reliable data transmission over 1 meter or more of
FR-4 and 15 meters or more of unequalized copper
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
To summarize, the XRT10L24 port multiplier device
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.
OVERVIEW OF PORT MULTIPLIER LOGIC
XRS10L140 port multiplier is a multiplexer where one
active host connection is multiplexed to multiple
device connections. The XRS10L140 is an extensible
design that can support up to 4 device connections
and utilizes the full bandwidth of the host connection.
XRS10L140 uses four bits, known as the PM Port
field in all Serial ATA frame types, to route frames
between the selected host and the appropriate
device. PM ports 0 through 3 are valid device ports
within the 4-output XRS10L140, while PM port 15 is
designated for communication between the host and
the XRS10L140 itself. For host-to-device
transactions, the PM Port field is designated by the
host in order to specify which device the frame is
intended for. For device-to-host transactions, the
XRS10L140 fills in the PM Port field with the port
address of the device that is transmitting the frame.
The XRS10L140 is compliant with the following
• Serial ATA, Revision 1.0a
• Serial ATA II: Extensions to Serial ATA 1.0a,
• Serial ATA II PHY Electrical Specifications,
• Serial ATA II: Port Multiplier, Revision 1.2
• Serial ATA Enclosures
• Other Serial ATA link replicator applications
• Buffers for externally connected links
• High density storage boxes
• RAID Subsystems
• Five independent 3/1.5G SATA ports.
• Supports 3/1.5G rate detection/speed negotiation.
• Supports power down modes - Active, partial,
slumber and power down.
PORT MULTIPLIER LOGIC FEATURES
• Low latency architecture.
• Supports OOB signaling for SATA applications.
Internal OOB detectors for COMSAS, COMRESET/
COMINIT and COMWAKE.
TEST AND CONTROL FEATURES
• Supports MDIO Bus.
• Outputs for various failure modes.
• Built-In self test mode through the MDIO bus.
• Supports various loopback modes.
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510) 668-7000 • FAX (510) 668-7017 • www.exar.com