TDA3MV_17 Datasheet, PDF (241/256 Pages) Texas Instruments – SoC for Advanced Driver Assistance Systems (ADAS) 15mm Package (ABF) Silicon Revision 2.0

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TDA3MV, TDA3MA
TDA3LX, TDA3LA
SPRS964C – JUNE 2016 – REVISED JULY 2017
DQ and DM
Dn
n = 0, 1, 2
SPRS91v_PCB_DDR3_25
Figure 8-68. DQ/DM Routing With Any Number of Allowed DDR3 Devices
8.9.2.15 Routing Specification
8.9.2.15.1 CK and ADDR_CTRL Routing Specification
Skew within the CK and ADDR_CTRL net classes directly reduces setup and hold margin and, thus, this
skew must be controlled. The only way to practically match lengths on a PCB is to lengthen the shorter
traces up to the length of the longest net in the net class and its associated clock. A metric to establish
this maximum length is Manhattan distance. The Manhattan distance between two points on a PCB is the
length between the points when connecting them only with horizontal or vertical segments. A reasonable
trace route length is to within a percentage of its Manhattan distance. CACLM is defined as Clock Address
Control Longest Manhattan distance.
Given the clock and address pin locations on the processor and the DDR3 memories, the maximum
possible Manhattan distance can be determined given the placement. Figure 8-69 and Figure 8-70 show
this distance for three loads and two loads, respectively. It is from this distance that the specifications on
the lengths of the transmission lines for the address bus are determined. CACLM is determined similarly
for other address bus configurations; that is, it is based on the longest net of the CK/ADDR_CTRL net
class. For CK and ADDR_CTRL routing, these specifications are contained in Table 8-44.
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Applications, Implementation, and Layout 241
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