LXT974/LXT975
Fast Ethernet 10/100 Quad Transceivers
Datasheet
The LXT974 and LXT975 are four-port PHY Fast Ethernet Transceivers which support IEEE
802.3 physical layer applications at both 10 Mbps and 100 Mbps. They provide all of the active
circuitry to interface four 802.3 Media Independent Interface (MII) compliant controllers to
10BASE-T and/or 100BASE-TX media.
This data sheet applies to all versions of the LXT974 and LXT975 products including
LXT974A, LXT974B, LXT975A, and LXT975B. As a result of product changes, Revision 4
parts are labeled LXT974B and LXT975B. Revision 3 parts are labeled LXT974A and
LXT975A. The differences in these product revisions are described in the LXT974/975
Specification Update.
All four ports on the LXT974 provide a combination twisted-pair (TP) or pseudo-ECL (PECL)
interface for a 10/100BASE-TX or 100BASE-FX connection.
The LXT975 is pin compatible with the LXT974 except for the network ports. The LXT975 is
optimized for dual-high stacked RJ-45 modular applications and provides a twisted-pair
interface on every port, but the PECL interface on only two.
The LXT974/975 provides three separate LED drivers for each of the four PHY ports and a
serial LED interface. In addition to standard Ethernet, each chip supports full- duplex operation
at 10 Mbps and 100 Mbps. The LXT974/975 requires only a single 5V power supply. The MII
may be operated independently with either a 3.3V or 5V supply.
Applications
■ 10BASE-T, 10/100-TX, or 100BASE- ■ LXT975 optimized for dual-high stacked
FX Switches and multi-port NICs.
modular RJ-45 applications.
Product Features
■ Four independent IEEE 802.3-
compliant 10BASE-T or 100BASE-
TX ports in a single chip.
■ Configurable LED drivers and serial LED output.
■ Configurable through MII serial port or via
external control pins.
■ 100BASE-FX fiber-optic capable.
■ Available in 160-pin PQFP with heat spreader.
■ Commercial temperature range (0-70oC
■ Standard CSMA/CD or full-duplex
operation.
ambient).
■ Supports auto-negotiation and legacy
systems without auto-negotiation
capability.
■ Part numbers:
—LXT974AHC
—LXT974BHC
—LXT975AHC
—LXT975BHC
■ Baseline wander correction.
■ 100BASE-TX line performance over
130 meters.
As of January 15, 2001, this document replaces the Level One document
LXT974/LXT975 Fast Ethernet 10/100 Quad Transceivers.
Order Number: 249274-001
January 2001
INTEL [ INTEL ]
