SPRS989F December 2016 – December 2018 DRA74P , DRA75P
PRODUCTION DATA.
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The region of the PCB used for the DDR2 circuitry must be isolated from other signals. The DDR2 keepout region is defined for this purpose and is shown in Figure 7-53. The size of this region varies with the placement and DDR routing. Additional clearances required for the keepout region are shown in Table 7-32.
The region shown in Table 7-32 should encompass all the DDR2 circuitry and varies depending on placement. Non-DDR2 signals should not be routed on the DDR signal layers within the DDR2 keepout region. Non-DDR2 signals may be routed in the region, provided they are routed on layers separated from DDR2 signal layers by a ground layer. No breaks should be allowed in the reference ground layers in this region. In addition, the vdds_ddrx power plane should cover the entire keepout region. Routes for the two DDR interfaces must be separated by at least 4x; the more separation, the better.