Data Sheet
MARCH 2000
Revision 1.6
LXT908
Universal 3.3V 10BASE-T and AUI Transceiver
General Description
Features
The LXT908 Universal 10BASE-T and AUI Transceiver is
designed for IEEE 802.3 physical layer applications. It
provides all the active circuitry to interface most standard
802.3 controllers to either the 10BASE-T media or
Attachment Unit Interface (AUI). In addition to standard
10 Mbps Ethernet, the LXT908 also supports full-duplex
operation at 20 Mbps.
Functional Features
LXT908 functions include Manchester encoding/decoding,
receiver squelch and transmit pulse shaping, jabber, link
testing and reversed polarity detection/correction. The
LXT908 can be used to drive either the AUI drop cable or
the 10BASE-T twisted-pair cable with only a simple
isolation transformer. Integrated filters simplify the design
work required for FCC-compliant EMI performance.
Convenience Features
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The LXT908 is fabricated with an advanced CMOS
process and requires only a single 3.3V power supply.
Applications
Improved Filters - Simplifies FCC Compliance
Integrated Manchester Encoder/Decoder
10BASE-T compliant Transceiver
AUI Transceiver
Supports Standard and Full-Duplex Ethernet
Automatic/Manual AUI/RJ-45 Selection
Automatic Polarity Correction
SQE Disable/Enable function
Power Down Mode with tristated outputs
Four loopback modes
Single 3.3V operation
Available in 64-pin LQFP and 44-pin PLCC package
Commercial (0 to +70°C) and
Extended (-40 to +85°C) temperature range
Diagnostic Features
• 10BASE-T Hub and Switching products
• Four LED Drivers
• AUI/RJ-45 Loopback
• Computer/workstation 10BASE-T LAN adapter boards
LXT908 Block Diagram
AUTOSEL
MD0
MD1
MD2
MODE SELECT LOGIC Controller
Compatibility/
Port Select /
Loopback /
Link test
PAUI
LBK
LI
TCLK
CLKI
WATCHDOG
TIMER
XTAL
OSC
CLKO
TEN
TWISTED PAIR
INTERFACE
Select:
PLS Only
or
PLS / MAU
RC
CMOS
TX
AMP
PULSE SHAPER
AND FILTER
RC
DO
COLLISION/
POLARITY
DETECT
CORRECT
MANCHESTER
ENCODER
TPOPB
TPOPA
TPONA
TPONB
RX
SLICER
TPIP
TPIN
TXD
DROP CABLE
INTERFACE
CD
LEDL
ECL
TX
AMP
SQUELCH / LINK
DETECT
+
DOP
DON
LPBK
RXD
DI
MANCHESTER
DECODER
RCLK
DIP
RX SLICER
DIN
CI
COLLISION LOGIC
COLLISION
RECEIVER
CIP
CIN
COL
LEDR LEDT/PDN
LEDC/FDE
DSQE
NTH JAB
PLR
Refer to www.level1.com for most current information.
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