AM3359, AM3358, AM3357
AM3356, AM3354, AM3352
SPRS717F –OCTOBER 2011–REVISED APRIL 2013
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5.6.2.2.3 DDR2 CK and ADDR_CTRL Routing
Figure 5-44 shows the topology of the routing for the CK and ADDR_CTRL net classes. The length of
signal path AB and AC should be minimized with emphasis to minimize lengths C and D such that length
A is the majority of the total length of signal path AB and AC.
A1
T
A
AM335x
A1
Figure 5-44. CK and ADDR_CTRL Routing and Topology
Table 5-54. CK and ADDR_CTRL Routing Specification(1)(2)
NO.
1
PARAMETER
MIN
TYP
MAX
2w
UNIT
Center-to-center CK spacing
2
CK differential pair skew length mismatch(2)(3)
25
mils
mils
3
CK B-to-CK C skew length mismatch
25
4
Center-to-center CK to other DDR2 trace spacing(4)
CK and ADDR_CTRL nominal trace length(5)
4w
5
CACLM-50
CACLM
CACLM+50
100
mils
mils
mils
6
ADDR_CTRL-to-CK skew length mismatch
7
ADDR_CTRL-to-ADDR_CTRL skew length mismatch
Center-to-center ADDR_CTRL to other DDR2 trace spacing(4)
Center-to-center ADDR_CTRL to other ADDR_CTRL trace spacing(4)
ADDR_CTRL A-to-B and ADDR_CTRL A-to-C skew length mismatch(2)
ADDR_CTRL B-to-C skew length mismatch
100
8
4w
3w
9
10
11
100
100
mils
mils
(1) CK represents the clock net class, and ADDR_CTRL represents the address and control signal net class.
(2) Series terminator, if used, should be located closest to the AM335x device.
(3) Differential impedance should be Zo x 2, where Zo is the single-ended impedance defined in Table 5-46.
(4) 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.
(5) CACLM is the longest Manhattan distance of the CK and ADDR_CTRL net classes.
Figure 5-45 shows the topology and routing for the DQS[x] and DQ[x] net classes; the routes are point to
point. Skew matching across bytes is not needed nor recommended.
DQ[0]
A1
DQ[1]
AM335x
Figure 5-45. DQS[x] and DQ[x] Routing and Topology
168
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