AM3874_15 Datasheet, PDF (287/361 Pages) Texas Instruments – AM387x Sitara™ ARM Processors

AM3874, AM3871
www.ti.com
SPRS695C – SEPTEMBER 2011 – REVISED DECEMBER 2013
8.13.4.1.2 DDR2 CK and ADDR_CTRL Routing
Figure 8-52 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 8-52. CK and ADDR_CTRL Routing and Topology
Table 8-63. CK and ADDR_CTRL Routing Specification ⁽¹⁾
NO.
PARAMETER
1 Center-to-center CK-CK spacing
2 CK/CK skew⁽¹⁾
3 CK A-to-B/A-to-C skew length mismatch⁽²⁾
4 CK B-to-C skew length mismatch
5 Center-to-center CK to other DDR2 trace spacing⁽³⁾
6 CK/ADDR_CTRL nominal trace length⁽⁴⁾
7 ADDR_CTRL-to-CK skew length mismatch
8 ADDR_CTRL-to-ADDR_CTRL skew length mismatch
9 Center-to-center ADDR_CTRL to other DDR2 trace spacing⁽³⁾
10 Center-to-center ADDR_CTRL to other ADDR_CTRL trace spacing⁽³⁾
11 ADDR_CTRL A-to-B/A-to-C skew length mismatch⁽²⁾
12 ADDR_CTRL B-to-C skew length mismatch
MIN
4w
CACLM-50
4w
3w
TYP
MAX UNIT
2w
25 Mils
25 Mils
25 Mils
CACLM
CACLM+50 Mils
100 Mils
100 Mils
100 Mils
100 Mils
(1) The length of segment A = A' + A′′ as shown in Figure 8-52.
(2) Series terminator, if used, should be located closest to the processor.
(3) Center-to-center spacing is allowed to fall to minimum (w) 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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