112
Memory Controller
NOTES:
1. TL1 and TL4 are approximately the same length allowing Rs in the middle of the lead-in trace between the
controller and SDRAM.
2. When controller to SDRAM lead-in traces are less than 6” the series resistor may be places anywhere in
between the center of the lead-in trace to SDRAM.
Table 67.
DDR II 400 Embedded DQS Lengths
Traces
Description
Layer
Minimum
Length
Maximum
Length
Trace
Impedance
Spacing Notes
TL0
Breakout
Microstrip
0”
0.5”
5 mils
5 mils trace width OK for
breakout.
TL1
Lead-in
Stripline
1 “
4”
Differential
impedance of
100 ohms
+/-15%
20 mils
from
others
TL2
Microstrip
0”
0.1”
5 mils trace width OK for
termination fan out
TL3
Microstrip
0”
0.1”
Same as TL2
TL4
Same as TL1
Stripline
1 in
4”
Differential
impedance of
100 ohms
+/-15%
20 mils
from
others
Same as TL1
Figure 56.
DDR II 400 Embedded DQS Topology
SDRAM
TL0
TL1
TL2
TL3
TL4
Rs 22 ohms +/- 5%
Rs 22 ohms +/- 5%***
Содержание 80331
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