DM9000A_06 DAVICOM [Davicom Semiconductor, Inc.], DM9000A_06 Datasheet - Page 52

• Manufacturer Part Number: DM9000A_06
• Description: Ethernet Controller with General Processor Interface
• 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 DM9000A 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 DM9000A.. There
should be no power or ground planes in the area under the
11.2 10Base-T/100Base-TX Auto MDIX Application
Final
Version: DM9000A-17-DS-F01
May 10, 2006
DM9000A
AVDD_25
AVDD_25
BGGND
BGRES
TX0+
TX0-
RXI+
RXI-
48
4
2
9
7
8
1
3
2.5V AVCC
AGND
1%
6.8K
50
1%
50
1%
50
220µF
AGND
1%
50
Figure 11-1 Auto MDIX Application
1%
0.1µF
AGND
0.1µF
0.1µF
Ethernet Controller with General Processor Interface
AUTO MDI-X
Transformer
network side of the transformer to include the area under the
RJ-45 connector. (Refer to Figure 11-4 and 11-5) 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 1 and 48 as possible (refer to Figure 11-1 and 11-2).
The designer should not run any high-speed signal near the
Band Gap resistor placement.
1:1
1:1
0.1µF/2KV
1%
75
1%
75
Chasis GND
DM9000A
1%
75
1
2
4
5
7
3
6
8
RJ45
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