Contents

4

Datasheet

Document #: 249115

Revision #: 003

Rev. Date: 08/07/01

4.2.3

Power and Ground Plane Layout Considerations.................................................. 33

4.2.4

Chassis Ground ..................................................................................................... 34

4.2.5

The RBIAS Pin....................................................................................................... 34

4.2.6

MII Terminations .................................................................................................... 35

4.2.7

Twisted-Pair Interface............................................................................................ 36

4.2.7.1

Magnetics Information............................................................................ 36

4.2.8

Clock......................................................................................................................37

4.2.9

LED Circuits........................................................................................................... 39

4.2.9.1

Direct Drive LEDs .................................................................................. 39

4.2.9.2

LED Pins Multiplexed with Configuration Inputs .................................... 39

4.2.9.3

Serial LEDs ............................................................................................ 40

4.3

Inter-Repeater Backplane Compatibility ............................................................................. 41

4.3.1

Local Backplane—3.3V Only ................................................................................. 41

4.3.2

Stack Backplane—3.3V or 5V ............................................................................... 41

4.3.2.1

3.3V-Only Stacks ................................................................................... 41

4.3.2.2

For 5V Backwards Stackability .............................................................. 41

4.3.2.3

3.3V and 5.0V Stacking Boards Cannot Be Mixed ................................ 41

5.0

Test Specifications...................................................................................................................... 44

6.0

Mechanical Specifications.......................................................................................................... 56

Figures

1

LXT98x3 Block Diagram............................................................................................................... 7

2

LXT9883 Pin Assignments ........................................................................................................... 8

3

Typical LXT9883 Repeater Architecture .................................................................................... 17

4

MII Interface................................................................................................................................ 19

5

Serial LED Shift Loading ........................................................................................................... 22

6

Serial LED Port Signaling ........................................................................................................... 23

7

100M IRB Connection ................................................................................................................ 29

8

IRB Block Diagram .................................................................................................................... 30

9

LXT9883 MII Operation .............................................................................................................. 32

10

Power and Ground Connections ................................................................................................ 35

11

Typical Twisted-Pair Port Interface and Power Supply Filtering ................................................ 38

12

Typical Reset Circuit .................................................................................................................. 38

13

LED Circuits - Direct Drive & Multiplexed Configuration Inputs .................................................. 39

14

Serial LED Circuit ....................................................................................................................... 40

15

100M Backplane Connection between LXT98x and LXT98x3 ................................................... 42

16

Typical 100 Mbps IRB Implementation ...................................................................................... 43

17

Typical 10 Mbps IRB Implementation ........................................................................................ 43

18

100 Mbps TP Port-to-Port Delay Timing..................................................................................... 48

19

100BASE-TX MII-to-TP Port Timing .......................................................................................... 49

20

100BASE-TX TP-to-MII Timing ................................................................................................. 50

21

10BASE-T MII-to-TP Timing ...................................................................................................... 51

22

10BASE-T TP-to-MII Port Timing .............................................................................................. 52

23

100 Mbps TP-to-IRB Timing ...................................................................................................... 53

24

10 Mbps TP-to-IRB Timing ........................................................................................................ 54

25

10 Mbps IRB-to-TP Port Timing ................................................................................................55

26

LXT98x3 Package Specifications .............................................................................................. 56