
Preliminary Data Sheet
July 2000
LU3X31FT Single-Port 3 V
10/100 Ethernet Transceiver TX/FX
Overview
The LU3X31FT is an integrated 10/100 Mbits/s phys-
ical layer device with an integrated transceiver. This
part was designed for 10/100 Mbits/s applications
where board space, cost, and power are at a pre-
mium and stringent functional interoperability is a
necessity. Operating at 3.3 V, the LU3X31FT is a
powerful device for the forward migration of legacy
10 Mbits/s products and noncompliant (does not
have autonegotiation) 100 Mbits/s devices. The
LU3X31FT was designed from the beginning to con-
form fully with all pertinent specifications, from the
ISO
*
/IEC 11801 and EIA
/TIA 568 cabling guidelines
to ANSI
X3.263 TP-PMD to IEEE
§
802.3 Ethernet
specifications.
Features
I
Single-chip integrated physical layer and trans-
ceiver for 10Base-T and/or 100Base-T functions.
I
IEEE 802.3 compatible 10Base-T and 100Base-T
physical layer interface and ANSIX3.263 TP-PMD
compatible transceiver.
I
PECL interface for external FX transceiver.
I
Built-in analog 10 Mbits/s receive filter, removing
the need for external filters.
I
Built-in 10 Mbits/s transmit filter.
I
10 Mbits/s PLL exceeding tolerances for both pre-
amble and data jitter.
I
100 Mbits/s PLL, combined with the digital adap-
tive equalizer, robustly handles variations in rise-
fall time, excessive attenuation due to channel
loss, duty-cycle distortion, crosstalk, and baseline
wander.
I
Transmit rise-fall time manipulated to provide lower
emissions, amplitude fully compatible for proper
interoperability.
I
Programmable scrambler seed for better FCC
compliancy.
I
Selectable CIM, Class II support, and powerful MII
drivers for repeater applications.
I
IEEE 802.3u Clause 28 compliant autonegotiation
for full 10M and 100M control.
I
Fully configurable via pins and management
accesses.
I
Extended management support with interrupt
capabilities.
I
PHY MIB support.
I
Symbol mode option.
I
Full LED support.
I
Low power consumption 150 mA max.
I
80-pin MQFP and 80-pin LQFP packages.
* ISO is a registered trademark of The International Organization
for Standardization.
EIAis a registered trademark of The Electronic Industries Asso-
ciation.
ANSI s a registered trademark of The American National Stan-
dards Institute, Inc.
§IEEE s a registered trademark of The Institute of Electrical and
Electronics Engineers, Inc.