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Ddr2 connection

Daniel Cardenas
Intellectual 730 points
Other Parts Discussed in Thread: OMAP-L138, OMAPL138

Hello,

I know it could be dummie questions, but I still have to do it.

I am designing a pcb with the omap-l138 processor and a ddr2 memory. First at all I understand that the routing is in the first layer, only, ¿Is that right?

Secondly, there is a zone called keep out region and let's suppose that this region has an area: (A.P.), and is smaller that the layout area, I guess that the ground area below the first layer should match with the A.P. position, but, CanI  use the rest area in the first and second(ground) and power layer (the third layer) outside the keep out region?

I guess the answer to both questions is: yes, but I have to be sure, if there is something that I should keep in mind, please tell me.

Thank you for your attention

Daniel

  • 0
    TI__Guru**** 178926 points

    Daniel

    Please refer to section 5.11.3 of the OMAPL138 data sheet for routing guideline.

    You don't have to route all the DDR signals on the first layer, as long as all the route constraints listed in section 5.11.3 have been met, you can route on other layers to avoid routing congestion.

    The keepout region is to isolate DDR signals from other non-DDR signals. You need to have solid ground beneath the keepout region so DDR signals would have a return path. But this would apply to other non-DDR signals as well. You also want a ground plane as large as possible, not just limit to the AP area. You can route other signals outside this keep out region.

    Thanks

    David