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Intel
®
820E Chipset
R
Design Guide 113
For noise-free and stable operation, place the crystal and associated discretes as close as possible to the
Intel
82562EH component, keeping the length as short as possible. Do not route any noisy signals in this
area.
2.22.3.4. Phoneline HPNA Termination
The transmit/receive differential-signal pair is terminated with a pair of 51.1 Ω (1%) resistors. This
parallel termination should be placed close to the Intel
82562EH component. The center, common point
between the 51.1
Ω resistors is connected to a voltage divider network. The opposite end of one, 806 Ω
resistor is tied to VCCA (3.3V), and the opposite end of the other 806
Ω resistor and the cap are
connected to ground. The termination is shown in the following figure.
Figure 70. Intel
®
82562EH Component Termination
1
2
3
4
5
6
TabTab
1
2
3
4
5
6
TabTab
8
Phone / modem
Shield ground
Line
8
7
7
IO_subsys_82562EH_term
1500 pF 1500 pF
6.8 µH
6.8 µH
6.8 µH6.8 µH
0
T
10
9
1
2
3
B6008
rx_tx_pn
rx_tx_n
0.022 µF
51.1
Ω
51.1
Ω
806
Ω
806
Ω
A+3.3 V
Tip
Ring
The filter and magnetics component T integrates the required filter network, high-voltage impulse
protection, and transformer to support the HomePNA LAN interface.
One RJ-11 jack (labeled LINE in the previous figure) allows the node to be connected to the phone line,
and the second jack (labeled PHONE in the previous figure) allows other down-line devices to be
connected at the same time. This second connector is not required by the HomePNA. However, typical
PCI adapters and PC motherboard implementations are likely to include it for user convenience.
A low-pass filter set up in line with the second RJ-11 jack also is recommended by the HomePNA, to
minimize interference between the HomeRun connection and a POTS voice or modem connection on the
second jack. This restricts the type of devices connected to the second jack, because the pass-band of this
filter is set at approximately 1.1 MHz. Please refer to the HomePNA website (www.homepna.org
) for up-
to-date information and recommendations regarding the use of this low-pass filter to meet HomePNA
certifications.