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LXD9781 PQFP Demo Board
6.0
Fiber Setup
6.1
Fiber Modules
The LXT9781 supports eight combination twisted-pair/fiber ports for 100BASE-FX operation.
Two Pseudo-ECL (PECL) interfaces are provided on the LXD9781 MII demo board for connection
to external fiber optic transceiver modules.
To setup the LXD9781 for 100BASE-FX evaluation, five external blue-wire connections and a
fiber-optic transceiver module (HP's HFBR-5903 or AMP's 269147-2) are required. Port
connections are shown in
•
Remove the associated twisted-pair transformer(s) and termination resistors. Once removed,
all associated ports will not operate in TP mode.
•
Connect ports 0 - 3 by removing transformer (T2) and termination logic (R272, R277, R280,
R285, R288, R293, R296, R301).
•
Connect ports 4 - 7 by removing transformer (T1) and termination logic (R240, R245, R248,
R253, R256, R261, R264, R269). Replace C220 - C235 with 0 Ω resistors.
•
Two fiber-module headers (JP37 and JP38) are provided for the blue-wire connection. Connect
ports 0 - 3 to fiber header JP37 and connect ports 4 - 7 to fiber header JP38.
•
Solder the fiber modules on the board. Fiber module F1 supports ports 0 - 3. Fiber module F2
supports ports 4 - 7.
•
Configure the port MDIO registers for Fiber Mode.
Table 16. MII Port Connections for Fiber Module Operation
Port
Header
0
JP36
1
JP35
2
JP34
3
JP33
4
JP32
5
JP31
6
JP30
7
JP28
18
Table
16.
Termination Logic
R296, R301, C222, C223
R288, R298, C220, C221
R280, R285, C226, C227
R272, R277, C224, C225
R264, R269, C230, C231
R256, R261, C228, C229
R248, R245, C234, C235
R240, R245, C232, C233
Fiber
Transformer
Header
T2
JP37
T1
JP38
Developer Manual
Fiber
Module
F1
F2
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