dm9000b Davicom Semiconductor, Inc., dm9000b Datasheet - Page 49

• Manufacturer Part Number: dm9000b
• Description: Ethernet Controller With General Processor Interface
• Manufacturer: 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 DM9000B 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 DM9000B.. There should be no
power or ground planes in the area under the network side
11.2 10Base-T/100Base-TX Auto MDIX Application
Final
Version: DM9000B-13-DS-F02
June 4, 2009
Figure 11-1 Auto MDIX Application
Ethernet Controller with General Processor Interface
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.
DM9000B
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