DM385, DM388
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SPRS821D –MARCH 2013–REVISED DECEMBER 2013
8.13.2.3 DDR2 CK and ADDR_CTRL Routing
Figure 8-53 shows the topology of the routing for the CK and ADDR_CTRL net classes. The route is a
balanced T as it is intended that the length of segments B and C be equal. In addition, the length of A
(A'+A'') should be maximized.
A1
A1
B
C
A´´
T
A´
A = A´ + A´´
Figure 8-53. CK and ADDR_CTRL Routing and Topology
(1)
Table 8-57. CK and ADDR_CTRL Routing Specification
NO.
1
PARAMETER
MIN
TYP
MAX
2w
25
UNIT
Center-to-center CK-CK spacing
CK/CK skew(1)
2
Mils
Mils
Mils
3
CK A-to-B/A-to-C skew length mismatch(2)
25
4
CK B-to-C skew length mismatch
25
5
Center-to-center CK to other DDR2 trace spacing(3)
CK/ADDR_CTRL nominal trace length(4)
4w
6
CACLM-50
CACLM
CACLM+50
100
Mils
Mils
Mils
7
ADDR_CTRL-to-CK skew length mismatch
8
ADDR_CTRL-to-ADDR_CTRL skew length mismatch
Center-to-center ADDR_CTRL to other DDR2 trace spacing(3)
Center-to-center ADDR_CTRL to other ADDR_CTRL trace spacing(3)
ADDR_CTRL A-to-B/A-to-C skew length mismatch(2)
ADDR_CTRL B-to-C skew length mismatch
100
9
4w
3w
10
11
12
100
100
Mils
Mils
(1) The length of segment A = A' + A′′ as shown in Figure 8-53.
(2) Series terminator, if used, should be located closest to the device.
(3) Center-to-center spacing is allowed to fall to minimum (2w) for up to 500 mils of routed length to accommodate BGA escape and routing
congestion.
(4) CACLM is the longest Manhattan distance of the CK and ADDR_CTRL net classes.
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