91
Memory Controller
Notes:
1. Series termination is recommended in the center of the lead-in length
2. Parallel termination with single VTT Termination is preferred than split termination
3. For single VTT termination (preferred) the resistor value = 51 ohms +/- 5%
4. For split termination, the value of the resistors are 100 ohms +/- 5% to 2.5V and 100 ohms +/-
5% to Ground.
Figure 44.
Embedded DDR 333 DQ/DQS Topology
Rp
TL1
TL2
TL3
TL5
22 ohms
+/- 5%
51 ohms
+/- 5%
SDRAM
TL4
TL6
VTT
Table 47.
Embedded DDR 333 DQ/DQS Topology Lengths
Traces
Description
Layer
Minimum
Length
Maximum
Length
Trace
Impedance
Spacing
Notes
TL1
Breakout
Microstrip/
Stripline
0”
0.5”
-
5 mils
5 mil trace width
breakout OK
TL2
Lead-in
Stripline
1 “
4”
45 ohms +/-
15% or 50
ohms +/-
15%
12 mils
• WIthin the same
group >12 mils
• Any other groups
(DQ/DQS/Clock) >20
mils
TL3
Microstrip
0”
0.1”
-
5 mils
Fan out for series
termination
TL4
Microstrip
0”
0.1”
-
5 mils
Fan out for series
termination
TL5
VTT or Split
Termination
Microstrip
0.25”
0.5”
-
5 mils
Single VTT
termination in VTT
island is preferred
TL6
Same as
TL2
Stripline
1”
4”
Same as
TL2
12 mils
Same as TL2
Summary of Contents for 80331
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