I347-AT4 Datasheet, PDF (33/148 Pages) Intel Corporation – Intel® Ethernet Network Connection I347-AT4 Datasheet

Device Functionality—I347-AT4
MAC
PCS
System
Interface
(SGMII)
21_2.14 = 1b
PMA
PMD
Copper
Interface
Figure 9. Copper Line Loopback Data Path
3.3.3
External Loopback
For production testing, an external loopback stub allows testing of the complete data
path.
For 10BASE-T and 100BASE-TX modes, the loopback test requires no register writes.
For 1000BASE-T mode, register 18_6.3 must be set to 1b to enable the external
loopback. All copper modes require an external loopback stub.
The loopback stub consists of a plastic RJ-45 header, connecting RJ-45 pair 1, 2 to pair
3, 6 and connecting pair 4, 5 to pair 7, 8, as seen in Figure 10.
1
2
3
4
5
6
7
8
Figure 10. Loopback Stub (Top View With Tab Up)
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