Qdr Address Signal Trace Width/Spacing Routing; Qdr Address Signal Group Routing Guidelines - Intel IXP28XX Manual

Table 19.
Figure 29.
Hardware Design Guide
Downloaded from Elcodis.com electronic components distributor

QDR Address Signal Group Routing Guidelines

Parameter
Signal Group
Topology
Reference Plane
Characteristic Trace Impedance
Main Trunk
Branches
RTT
Nominal Trace Width
Main Trunk
Arms of the T
Nominal Trace Separation
Group Spacing
1
Trace length P +A to SRAMs
Trace length B, C
Trace length D
Trace length E, F
Maximum via count per signal
Length tuning method
1. P refers to the package length.
Figure 29 illustrates routing for a QDR address signal trace width/spacing.

QDR Address Signal Trace Width/Spacing Routing

T
d2
Other
T
signal
Signals
T
d1
Routing Guideline
Address
Balanced-T topology
Ground
34 Ω ±5%
60 Ω ±5%
35 Ω ±1%
10 mils
3.5 mils
15 - 20 mils
Isolation from all other signals is 20 - 25mils.
Should be matched to K-Clk trace length minus 0.9 inches.
Maximum = 11.0 inches
Trace length from ball to ball for all Address nets should be
matched for the entire group to within 25 mils.
As short as possible; B and C should match.
Maximum B + E = 1.0 inches
Maximum C + F = 1.0 inches
As short as possible; Maximum = 100 mils
As short as possible.
Maximum B + E = 1.0 inches
Maximum C + F = 1.0 inches
As small as possible; Maximum = 12 vias
All address signals matched within ±25 mils, where length
includes package length compensation (P+A)
POWER or GND Plane
20 mil or larger W
ADDRESS
Signa
Prepreg
POWER or GND Plane
IXP28XX Network Processor
QDR SRAM
S W
D2
ADDRESS
Signal
D1
3993-01
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