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AM623: What is the maximum memory bytes of LPDDR4 that can be used?

K.Z
Expert 2490 points
Part Number: AM623

Tool/software:

Hi All,

Regarding the LPDDR4 connection, see
The [AM62x data sheet] (P1/263) states 4GBytes with LPDDR4, but the [AM62x, AM62Lx DDR Board Design and Layout Guidelines] (P22/44) states Max2GBytes. Which is correct?
 [AM62x, AM62Lx DDR Board Design and Layout Guidelines] (P22/44) states that it is possible to connect the Dual specification with Single.
In this case, is it necessary to process the pins of the other memory area of LPDDR4?

Best Regards,

Ito

  • 0
    TI__Guru* 86580 points

    Hi Ito, it is technically possible to get 4GB of LPDDR4 with AM62x, however, as noted in the Layout guidelines, you would have to use a dual rank, dual channel LPDDR4 and only connect 1 rank to avoid splitting the data bus on the board.  Thus, you would not be able to access half of the memory.  

    So the layout guidelines suggests that if you are needing more than 2GB of memory, you should use DDR4.

    Regards,

    James

  • 0 in reply to JJD
    Expert 2490 points

    Hi James,

    Thank you for your reply.

    When using 4GB(Dual) of LPDDR4, do I need to process unused pins?

    Best Regards,

    Ito

  • +1 in reply to K.Z
    TI__Guru* 86580 points

    Hi Ito, you can leave most of the unused pins unconnected.  The unused DQS signals on the memory should be pulled to opposite polarity (ie, DQS_t pulled low, DQS_c pulled high) with a 1K resistor

    Regards,

    James