Intel
®
LXT915 Simple Quad Ethernet
Repeater
Datasheet
The Intel
®
LXT915 Simple Quad Ethernet Repeater is an integrated multi-port repeater designed
for mixed-media networks. It provides all the active circuitry required for the repeater function
in a single CMOS device. It includes one Attachment Unit Interface (AUI) port and four
10BASE-T transceivers. The AUI port allows connection of an external transceiver (10BASE-2,
10BASE-5, 10BASE-T or FOIRL) or a drop cable. The 10BASE-T transceivers are entirely self-
contained with internal filters that simplify the design work required for FCC-compliant EMI
performance.
An Inter-Repeater Backplane (IRB) interface allows 128 or more 10BASE-T ports to be
cascaded, creating a large single-segment multi-port repeater.
The LXT915 Repeater requires only a single 5-volt power supply due to its advanced CMOS
fabrication process.
Applications
■
Remote or Stand-alone Unmanaged Hubs
■
Stackable Unmanaged Hubs
Product Features
■
■
■
■
Four integrated 10BASE-T transceivers
and one AUI transceiver on a single chip
Six integrated LED drivers with four
unique operational modes
On-chip transmit and receive filtering
Automatic polarity detection and correction
■
■
■
Synchronous or asynchronous Inter-
Repeater Backplane supports “hot
swapping”
Inter-repeater backplane allows cascaded
repeaters, linking 128 or more 10BASE-T
ports
Packaged in 64-pin PQFP
Order Number:
249343-003
20-Dec-2005
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estoppel or otherwise, to any such patents, trademarks, copyrights, or other intellectual property rights.
The Intel
®
LXT915 Simple Quad Ethernet Repeater may contain design defects or errors known as errata which may cause the product to deviate
from published specifications. Current characterized errata are available on request.
Contact your local Intel sales office or your distributor to obtain the latest specifications and before placing your product order.
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Copyright © 2005, Intel Corporation. All Rights Reserved.
Datasheet
Intel
®
LXT915 Simple Quad Ethernet Repeater
Contents
1.0
2.0
Pin Assignments and Signal Descriptions
....................................................................7
Functional Description
.................................................................................................. 11
2.1
2.2
Introduction.......................................................................................................... 11
External Interfaces .............................................................................................. 11
2.2.1 10BASE-T Ports .....................................................................................11
2.2.2 AUI Port.................................................................................................. 11
2.2.3 Inter-Repeater Backplane ...................................................................... 11
2.2.3.1 Synchronous IRB Operation...................................................... 12
2.2.3.2 Asynchronous IRB Operation ....................................................12
Internal Repeater Circuitry .................................................................................. 12
Initialization.......................................................................................................... 13
10BASE-T Port Operation ................................................................................... 15
2.5.1 10BASE-T Reception ............................................................................. 15
2.5.2 Polarity Detection and Correction...........................................................15
2.5.3 10BASE-T Link Integrity Testing ............................................................ 15
2.5.4 10BASE-T Transmission ........................................................................ 15
AUI Port Operation .............................................................................................. 16
2.6.1 AUI Reception ........................................................................................ 16
2.6.2 AUI Transmission ................................................................................... 16
Collision Handling................................................................................................ 16
LED Display......................................................................................................... 16
2.8.1 LED Mode 0 (Default)............................................................................. 16
2.8.2 LED Mode 1 ........................................................................................... 17
2.8.3 LED Mode 2 ........................................................................................... 17
2.8.4 LED Mode 3 ........................................................................................... 17
2.3
2.4
2.5
2.6
2.7
2.8
3.0
Application Information
.................................................................................................20
3.1
Layout Requirements ..........................................................................................20
3.1.1 The Twisted Pair Interface ..................................................................... 20
3.1.2 The RBIAS Pin ....................................................................................... 20
Unmanaged Hub Application............................................................................... 20
Magnetics Requirements.....................................................................................24
3.3.1 The Twisted Pair Interface ..................................................................... 24
3.3.2 Component Selection ............................................................................. 24
3.2
3.3
4.0
5.0
Test Specifications.........................................................................................................
25
Mechanical Specifications.............................................................................................
29
5.1
Top Label Markings............................................................................................. 30
6.0
Ordering Information
..................................................................................................... 31
Datasheet
3
Intel
®
LXT915 Simple Quad Ethernet Repeater
Figures
1
2
3
4
5
6
7
8
9
10
11
12
Block Diagram ....................................................................................................... 6
Pin Assignments ................................................................................................... 7
Global State Machine .......................................................................................... 13
Partitioning State Diagram .................................................................................. 14
Integrated LED Driver Indications ....................................................................... 19
8-Port Unmanaged Hub Application, LED Mode 1 Selected (1 of 2) .................. 22
8-Port Unmanaged Hub Application LED Mode 1 Selected (2 of 2) ................... 23
Inter-Repeater Bus Timing .................................................................................. 28
Package Specifications ....................................................................................... 29
Sample HQFP Package – Intel
®
SLXT915QC Repeater .................................... 30
Sample Pb-Free (RoHS-Compliant) HQFP Package – Intel
®
EGLXT915QC Re-
peater30
Ordering Information Matrix – Sample ................................................................ 32
Tables
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Twisted-Pair Port Signal Descriptions ................................................................... 8
AUI Port Signal Descriptions ................................................................................. 8
Control, Status and Miscellaneous Signal Descriptions ........................................ 8
Inter-Repeater Backplane Signal Descriptions ..................................................... 9
Power Supply Signal Descriptions ...................................................................... 10
LED Mode Selection ........................................................................................... 17
Mode 0 LED Truth Table (Default) ...................................................................... 17
Mode 1 LED Truth Table ..................................................................................... 17
Mode 2 LED Truth Table ..................................................................................... 18
Mode 3 LED Truth Table ..................................................................................... 18
Manufacturers Magnetics List ............................................................................ 24
Absolute Maximum Ratings ................................................................................ 25
Recommended Operating Conditions ................................................................. 25
I/O Electrical Characteristics1 ............................................................................. 25
AUI Electrical Characteristics .............................................................................. 26
TP Electrical Characteristics ............................................................................... 26
IRB Electrical Characteristics .............................................................................. 26
Switching Characteristics .................................................................................... 27
Inter-Repeater Bus Timing .................................................................................. 28
Product Information ............................................................................................. 31
4
Datasheet
Intel
®
LXT915 Simple Quad Ethernet Repeater
Revision History
Date
20-Dec-2005
Revision
003
Page
7
30
31
32
February 2001
002
26
Description
Modified
Figure 2 “Pin Assignments” on page 7.
Added
Section 5.1, “Top Label Markings” on page 30.
Added
Table 20 “Product Information” on page 31.
Added
Figure 12 “Ordering Information Matrix – Sample” on
page 32.
I/O Electrical Characteristics table: Supply current
Under Max: Change value from 180 to 240.
Under Test Conditions: Add text: “100Ω test load, no LEDs”.
Add table note to value: Supply current may vary depending on the
transformer, LED, and resistor selections.
Swapped values for V
IH
and V
IHRESET.
Datasheet
5
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