
38
Hardware Design Guide
IXP28XX Network Processor
RDRAM
If the requirement cannot be guaranteed by the power sequence design then the following
recommendations can be used to meet the requirement:
•
Each channel’s V
TERM
can be linked to V
CCR_IO
with back-to-back Schottkey diodes. An
example of this implementation is shown in
Figure 8
.
•
The RDRAM V
CMOS
can be connected to V
CCR_IO
because V
CMOS
draws only a few µA.
3.3
IXP28XX Network Processor Rambus* Controller
Footprint and Via Placement
The following figures illustrate the IXP28XX network processor Rambus* controller footprint and
via placement:
•
Figure 9, “Rambus* Controller Footprint and Via Placement Showing Alternating Dogbone
Orientation”
•
Figure 10, “Rambus* Controller Footprint and Via Placement Showing Exploded View of
Checkerboard Detail”
Figure 9
illustrates the IXP28XX network processor Rambus* controller footprint and via
placement. The checkerboard GND-signal via placement is achieved by alternating the orientation
of the dogbones.
Figure 8.
Common V
CCR_IO
for All Three RACs in the IXP28XX
®
Network Processor
B3431-01
Common VCCRIO
Intel
®
IXP2800
Network
Processor
3 RACs
3 Vterms
HCD Module
HCD Module
HCD Module
Downloaded from
Elcodis.com
electronic components distributor