DM9000_09 DAVICOM [Davicom Semiconductor, Inc.], DM9000_09 Datasheet - Page 43

• Manufacturer Part Number: DM9000_09
• Description: ISA to Ethernet MAC Controller with Integrated 10/100 PHY
• Manufacturer: DAVICOM [Davicom Semiconductor, Inc.]

11. Application Notes
11.1 Network Interface Signal Routing
Place the transformer as close as possible to the RJ-45
connector. Place all the 50Ω resistors as close as possible
to the DM9000 RXI± and TXO± pins. Traces routed from
RXI± and TXO± to the transformer should run in close pairs
directly to the transformer. The designer should be careful
not to cross the transmit and receive pairs. As always, vias
should be avoided as much as possible. The network
interface should be void of any signals other than the TXO±
and RXI± pairs between the RJ-45 to the transformer and
the transformer to the DM9000..
power or ground planes in the area under the network side
11.2 10Base-T/100Base-TX Application
Final
Version: DM9000-DS-F03
April 23, 2009
DM9000
BGGND
BGRES
RXI+
TX0+
TX0-
RXI-
50Ω
29
30
33
34
26
25
1%
50Ω
1%
1%
50
Ω
1%
3.3V AVDD
50
Ω
AGND
There should be no
6.8KΩ, 1%
AGND
3.3V AVCC
AGND
AGND
0.1μF
0.1μF
0.1μF
0.1μF
AGND
ISA to Ethernet MAC Controller with Integrated 10/100 PHY
Figure 11-1
Transformer
1:1
1:1
of the transformer to include the area under the RJ-45
connector. (Refer to Figure 4 and 5) Keep chassis ground
away from all active signals. The RJ-45 connector and any
unused pins should be tied to chassis ground through a
resistor divider network and a 2KV bypass capacitor.
The Band Gap resistor should be placed as physically close
as pins 25 and 26 as possible (refer to Figure 1 and 2).
The designer should not run any high-speed signal near the
Band Gap resistor placement.
75Ω
1%
1%
75
Ω
1%
75
Ω
Chasis GND
0.1μF/2KV
1%
75
Ω
3
6
4
5
7
1
2
8
DM9000
RJ45
43