84
Memory Controller
NOTE:
Length matching should be done from die to DIMM connector
1. Between intra pairs +/- 25 mils
2. Between clock pairs M_CK0, M_CK1, M_CK2 +/- 100mils on unbuffered clocks
3. DQS lengths are /- 1.5 “ max. of MCK for stripline
4. DQS lengths are /- 1.0 “ max. of MCK for stripline
5. Address/Command/Control lengths are with-in 2” to 3” less than MCK
6. Any address/command/control lengths greater than M_CK from die to DIMM is not guaranteed for x2 bank
unbuffered configurations.
Table 42.
DDR 333 Unbuffered DIMM Clock Topology Lengths
Traces
Description
Layer
Minimum
Length
Maximum
Length
Trace
Impedance
Spacing
Notes
TL1
(all 3
clock
pairs)
Breakout
Microstrip
0.5”
5 mils
5 mils trace width OK for
breakout.
TL2
(all 3 x
clock
pairs)
Lead-in
Microstrip/
Stripline
2 “
10”
Differential
Impedance 100
ohms +/- 15%
20 mils
from
others
•
Route as differential pairs.
•
Series termination of 22
ohms +/- 5%.
Figure 41.
DDR 333 Unbuffered DIMM Clock Topology
184 pin DIMM Connec tor
Pins 137 & 138
TL1_CK0
22 ohms +/- 5%
22 ohms +/- 5%
22 ohms +/- 5%
22 ohms +/- 5%
22 ohms +/- 5%
22 ohms +/- 5%
TL2_CK0
TL1_CK1
TL2_CK1
TL1_CK2
TL2_CK2
Cloc k Pair CK0
Clock Pair CK1
Clock Pair CK2
184 pin DIMM Connector
Pins 16 & 17
184 pin DIMM Connector
Pins 76 & 75
Содержание 80331
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