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SMSC 80 Arkay Drive, Hauppauge, NY 11788
For RoHS compliance and environmental information, please visit www.smsc.com/rohs
SMSC Literature #CP-HUB-037-12/07-1
Copyright ©2007 SMSC or its subsidiaries. All rights reserved. Although
the information in this document has been checked and is believed to be
accurate, no responsibility is assumed for inaccuracies. SMSC reserves
the right to make changes to product descriptions and specifications at
any time without notice. Contact your local SMSC sales office to obtain
the latest specifications before placing your product order. The provision
of this information does not convey any licenses under any patent rights
or other intellectual property rights of SMSC or others. All sales are ex-
pressly conditional on your agreement to the terms and conditions of the
most recently dated version of SMSC’s standard Terms of Sale Agreement
dated before the date of your order. Products may contain design defects
or errors known as anomalies which may cause a product’s functions to
deviate from published specifications. Anomaly sheets are available upon
request. SMSC products are not designed, intended, authorized or war-
ranted for use in any life support or other application where product failure
could cause or contribute to personal injury or severe property damage.
Any and all such uses without prior written approval of an Officer of SMSC
and further testing and/or modification will be fully at the risk of the cus-
tomer. Copies of this document or other SMSC literature, as well as the
Terms of Sale Agreement, may be obtained by visiting SMSC’s website at
http://www.smsc.com. SMSC and the SMSC logo are registered trademarks
and MultiTRAK is a trademark of Standard Microsystems Corporation
(“SMSC”). Other names mentioned may be trademarks of their respective
holders. All claims made herein speak as of the date of this material. The
company does not undertake to update such statements. (6/07)
Which USB251x Family Member Is Right For Your Design?
SMSC MultiTRAK™ Technology
MultiTRAK utilizes a dedicated TT per port to maintain consistent Full-Speed
data throughput regardless of the number of active downstream connections.
MultiTRAK outperforms conventional USB 2.0 hubs with a single TT in USB
Full-Speed data transfers by up to 100%*, effectively doubling the amount
of data throughput for every downstream port.
*with a minimum of four Full-Speed bulk mass storage devices on a 4-port hub
700
600
500
400
300
200
100
0
Throughput (KB per sec)
Number of downstream Full-Speed connections
1 2 3 4
Single-TT Hub Multi-TT Hub
PortMap provides flexible port mapping and disable sequences. The
downstream ports of USB251x hubs can be reordered or disabled in any
sequence to support single-platform, multiple-SKU systems in managing
component population options. For any port that is disabled, the USB251x
automatically reorders the remaining ports to match the USB host controller’s
port numbering scheme.
PortSwap adds per-port programmability to USB differential-pair pin loca-
tions. PortSwap allows direct alignment of USB signals (D+/D-) to connectors
avoiding uneven trace length or crossing of the USB differential signals on
the PCB.
P1: Connected
P2: Connected
P3: Disabled
P4: Disabled
Disabled
Connected
Disabled
Connected
P1
P2
P3
P4
P0
Logical
Connection
USB PORT VIRTUALIZATION
Physical
Connection
TrueSpeed is a USB host/device port status indicator to provide visual
feedback on connection speed. Per-port, three-color LED drivers indicate
the speed of connected USB host and devices – Hi-Speed (480 Mbps), Full-
Speed (12 Mbps) and Low-Speed (1.5 Mbps).
PHYBoost enables programmable four-level USB signal drive strengths in
downstream port transceivers. PHYBoost attempts to restore USB signal
integrity that has been compromised by system level variables such as poor
PCB layout, long cables, etc. The graphics at the right show an example of
Hi-Speed USB eye diagrams before (PHYBoost at 0%) and after (PHYBoost
at 12%) signal integrity restoration in a compromised system environment.
High-Speed
Full-Speed
Low-Speed
LED
D+
D-
Chip
D-
D+
C31 J2
+
D-
D+
USB
Connector
C28
Chip
D+
D-
D-
D+
C25 C26
J2
USB
Connector
Before Boost After Boost
# Downstream Ports
MultiTRAK Technology
PortMap
PortSwap
TrueSpeed
PHYBoost
I2C/SMBus
-40° to 85°C
36QFN (6x6x0.9 mm)
48QFN (7x7x0.85mm)
RoHS compliant
USB2512 USB2512i USB2513 USB2513i USB2514 USB2514i