AM3359, AM3358, AM3357, AM3356, AM3354, AM3352
SPRS717H –OCTOBER 2011–REVISED MAY 2015
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Table 7-55. DQS[x] and DQ[x] Routing Specification
(1)
NO. PARAMETER MIN TYP MAX UNIT
1 Center-to-center DQS[x] spacing 2w
2 DQS[x] differential pair skew length mismatch
(2)
25 mils
3 Center-to-center DDR_DQS[x] to other DDR2 trace spacing
(3)
4w
4 DQS[x] and DQ[x] nominal trace length
(4)
DQLM-50 DQLM DQLM+50 mils
5 DQ[x]-to-DQS[x] skew length mismatch
(4)
100 mils
6 DQ[x]-to-DQ[x] skew length mismatch
(4)
100 mils
7 Center-to-center DQ[x] to other DDR2 trace spacing
(3)(5)
4w
8 Center-to-center DQ[x] to other DQ[x] trace spacing
(3)(6)
3w
(1) DQS[x] represents the DQS0 and DQS1 clock net classes, and DQ[x] represents the DQ0 and DQ1 signal net classes.
(2) Differential impedance should be Zo x 2, where Zo is the single-ended impedance defined in Table 7-46.
(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) There is no requirement for skew matching between data bytes; that is, from net classes DQS0 and DQ0 to net classes DQS1 and DQ1.
(5) Signals from one DQ net class should be considered other DDR2 traces to another DQ net class.
(6) DQLM is the longest Manhattan distance of each of the DQS[x] and DQ[x] net classes.
170 Peripheral Information and Timings Copyright © 2011–2015, Texas Instruments Incorporated
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