
72
Hardware Design Guide
IXP28XX Network Processor
QDR SRAM
Table 25
provides routing guidelines for the QDR K and K# signal groups.
Figure 35
illustrates routing for QDR K and K# signal trace width/spacing.
Figure 34.
QDR K and K# Routing Topology
!" #$
!!% #$
&
'()&
'
9
!* #+,
Table 25.
QDR K and K# Signal Group Routing Guidelines
Parameter
Routing Guideline
Signal Group
K, K#
Topology
Point-to-Point
Reference Plane
Ground
Characteristic Trace Impedance
50
Ω
±10%
RTT
50
Ω
±1%
Nominal Trace Width
5 mils
Nominal Trace Separation
20 mils
Group spacing
Isolation from all other signals is 20 - 25 mils
Trace length P
1
+A to SRAMs
1.
P refers to the package length.
Trace length from ball to ball should be within 25 mils for all K,
K# nets.
Trace length B
As short as possible.
Maximum = 1.0 inches
Maximum via count per signal
As short as possible.
Maximum = 6 vias
Length tuning method
K and K# signals matched within ±25 mils to (Data-Out + 0.5
in.), (A 0.9 in.), and (C 0.5 in.) signals, where
length includes package length compensation (P+A)
Downloaded from
Elcodis.com
electronic components distributor
Содержание IXP28 Series
Страница 10: ...IXP28XX Network Processor Revision History 10 Downloaded from Elcodis com electronic components distributor ...
Страница 126: ...126 Hardware Design Guide IXP28XX Network Processor PCI Downloaded from Elcodis com electronic components distributor ...
Страница 154: ...Index 154 Downloaded from Elcodis com electronic components distributor ...