132
Hardware Design Guide
IXP28XX Network Processor
Slowport
7.1.1.1.2
Slowport Clock Signals
Figure 79
illustrates the topology for the Slowport clock.
Table 49
provides routing guidelines for the Slowport media interface clock signals.
7.1.1.1.3
Slowport Address/Data Signals
Figure 80
illustrates the topology for Slowport address/data signals.
Figure 79.
Slowport Clock Topology
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Table 49.
Slowport Clock Signals Guideline
Parameter
Routing Guideline
Signal Group
Slowport Clock
Topology
Point-to-point
Reference Plane
Dual-referenced, PWR-SIG-GND
Characteristic Trace Impedance
60
Ω
±
10%
Nominal Trace Width
3.5 mils
Nominal Trace Separation
9 mils
Group spacing
Isolation from other signal groups is 20 mils.
IXP28XX breakout guideline
4 mil with 4-mil space for a maximum of 300 mils
Trace Length A
Maximum = 400 mils.
Trace Length B
Maximum = 5500 mils.
Trace Length C
Maximum = 250 mils.
Trace Length D
Maximum = 7000 mils.
Resistor - R
s
30.1
Ω
± 10%
Maximum Via Count per Signal
8 vias
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