82
Hardware Design Guide
IXP28XX Network Processor
QDR SRAM
Table 33
provides routing guidelines for the TCAM/SRAM/coprocessor interface base card.
4.7.1.1.2
C, C#, CIN, and CIN# Clocks Signals
Figure 46
illustrates the topologies for the C, C#, CIN, and CIN# clocks.
Figure 45.
Address, D, CONTROL, Q, and K-Clocks Topologies
B3960-01
MICTOR
Connector
MICTOR
Connector
A
Intel
®
IXP2800 Driver
Address
D, Parity-Out
RPE#, WPE#, BWE#
K/K#-Clocks
A
Intel
®
IXP2800 Receiver
Q, Parity-In
(On-Die Termination 50
Ω
)
Table 33.
TCAM/SRAM/Coprocessor Interface Guidelines (Address, D, CONTROL, Q, and K-
Clocks)
Parameter
Routing Guideline
Signal Group
TCAM/SRAM/coprocessor Address, D, CONTROL, Q, and
K-Clocks
Topology
Point-to-Point
Reference Plane
Ground
Characteristic Trace Impedance
50
Ω
±5%
Nominal Trace Width
5 mils
Nominal Trace Separation for group
8 to 15 mils
Group spacing
Isolation from non-QDR and non-group-related signals is
20 mils.
IXP28XX breakout guideline
3.5 mils with 4 mil space for a maximum of 400 mils
A or B trace length
Maximum = 5.0 inches (IXP28XX pin to Mictor* pin)
The trace length from ball-to-ball should be within 25 mils.
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