71
Memory Controller
1. Microstrip Differential Lines: Motherboard/Add-in 100 ohm: Constructed by two microstrips of 5 mils traces
separated by center to center distance of 13 mils as shown in
2. Strip Differential Lines: Motherboard Stripline 100 ohms: Constructed by two striplines of 4 mils traces
separated by center to center distance of 12 mils as shown in
3. Strip Differential Lines: Add-in stripline 100 ohms: Constructed by two striplines of 4 mils traces separated by
center to center distance of 13 mils as shown in
Table 31.
Example Topologies for DDR Trace
Topology
Trace Width
(mils)
Min Trace
Spacing
(mils)
Trace
Impedance
(ohms)
Preferred
signals
Board Type
Microstrip
(layers 1 or 8)
5
5
Breakout
Motherboard/Add-in
7
12
45
Address/
CMD/Control
Motherboard/Add-in
6
12
50
Motherboard/Add-in
4
12
60
Motherboard/Add-in
5 (note 1)
20
100 differential
Differential
Clock/DQS
Motherboard/Add-in
Stripline
(layers 3 or 6)
5
5
Break out
Motherboard/Add-in
6
12
45
DQ/DQS/CB
Motherboard
5
12
50
Motherboard card
7
12
45
DQ/DQS/CB
Add-in card
6
12
50
Add-in card
4
12
60
Add-in card
4 (note 2)
20
100 Ohm
Differential
Clocks
Motherboard*
5 (note 3)
20
100 Ohm
Differential
Clock
Add-in card*
Figure 35.
100 ohm Differential Trace
B2530-02
Other
Signals
Diff +
4/5 mils
20 mils Spacing
Diff -
Other
Signals
20 mils Spacing
4/5 mils
Center to Center
(12/13 mils
100
Ω
Differential Trace
Содержание 80331
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