TI TVS diode array
TPD4E05U06 with easy
routing pinout
T1
U6
Clearance between signal lines
and GND and Earth/Shield
Differential length matching
and routing for signals from
transformer to RJ45
Differential length matching
and routing for signals from
PHY to transformer
To ensure shortest routing of
the signals a layer change was
done due to pinout of RJ45
J4
Design Files
79
JAJU324B – March 2015 – Revised July 2017
翻訳版
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6.4.3
Layout for Differential Gigabit Ethernet Signals
From the PHY to the magnetics the differential pairs are routed on the top layer with differential
impedance control matching of 100
Ω
. The reference GND is on mid layer 1. This is achieved by ensuring
that isolation between top layer and mid layer 1 is smaller than the surrounding planes.
From the magnetics to the RJ45 the differential pairs A, C, and D are routed on the top layer while pair B
is routed on mid layer 2. This is due to crossing the signals on the RJ45 Ethernet jack. Again, the
differential pairs are impedance matched to 100
Ω
with reference to GND on mid layer 1. Due to the GND
being mid layer 1, there is no need for GND vias added around the B signal.
This routing achieves the minimum possible trace lengths from PHY to magnetics, magnetics to RJ45, and
here a maximum delta of the trace lengths of 1 mm between the differential pairs.
図
図
73. Layout Guidelines for PHY Differential Signals
