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AM6412: eMMC Electrical Standard 5.1

Kanae
Mastermind 9875 points
Part Number: AM6412

Hi Support Team,

The following question is from our customer who is designing using "MTFC32GAZAQHD-IT" as eMMC for "AM6412".

[Background of the question]

MTFC32GAZAQHD-IT" is a replacement for eMMC "MTFC16GAPALBH-IT" which is installed on the evaluation board.

There are two kinds of documents about pattern drawer for "MTFC32GAZAQHD-IT".
TN-FC-62 e.MMC PCB Design Guide 5.1.pdf
　⇒ The following description is considered to be the description for eMMC version 5.1.


TN-FC-35 e.MMC PCB Design Guide.pdf
⇒ The following description assumes that it is not eMMC version 5.1.


From the above, the reference material is considered to change depending on whether eMMC version 5.1 is supported or not.


[Question] 
In "TN-FC-62: e.MMC PCB Design Guide 5.1", the pattern for "MTFC32GAZAQHD-IT" is pulled out between BGA 0.5mm pitch pads,
but in "TN-FC-35: e.MMC PCB Design Guide" it is pulled out via NC pins.
The "TN-FC-35: e.MMC PCB Design Guide" shows the extraction via NC pins.

According to the following site, AM6412 eMMC is backward compatible,
so is it OK to pull it out via NC pins, using the material for non-eMMC version 5.1 as reference?

e2e.ti.com/.../am6412-does-the-am6412-support-the-jesd84-b51a- emmc-5-1-standard?

Best Regards,
Kanae

  • 0
    TI__Guru 59085 points

    I do not think the layout difference shown between the two application notes has anything to do with AM64x. This appears the difference is related to the route-through pins not being connected to anything inside older eMMC devices. I suspect the pins previously shown as route-through pins are connected to something inside newer eMMC devices, which prevents them from being used as route-through pins. Your customer should discuss this topic with Micron.

    Regards,
    Paul

  • 0 in reply to peaves
    Mastermind 9875 points

    Hi Paul,

    Thank you for your reply!
    I will share it with my customer.

    I would like to confirm one point, it is stated in the TRM and DS that
    the MMCSD Host Controller eMMC Electrical Standard 5.1 (JESD84-B51)
    for the AM64x eMMC interface is supported.
    In the "Multi-Media card features:" section, it says only HS200 is supported,
    but not HS400, so does this mean that the Multi-Media card does not support Standard 5.1 (JESD84-B51)?
    I feel sorry for my lack of knowledge about the standard, but I would appreciate it if you could tell me more about it.

    Best Regards,
    Kanae

  • +1 in reply to Kanae
    TI__Guru 59085 points

    In the timing section of the datasheet, we say: "MMC0 interface is compliant with the JEDEC eMMC electrical standard v5.1 (JESD84-B51) and supports the following eMMC applications:".

    In this reference, we do not mention host specification along with JESD84-B51 because this specification only applies to the eMMC device.

    It looks like portions of the TRM content was copied into the Detailed Descriptions chapter of the datasheet, where it makes the inappropriate association of host controller to the JESD84-B51 standard. I will need to discuss this with the TRM owner and have it fixed in the datasheet.

    I'm not aware of an eMMC specification that is specific to the host.   

    The eMMC standard defines many data transfer rates and the electrical and timing expectations for each. As mentioned above, the standard applies to the eMMC device not the host controller. It does not require a host to support all data transfer rates.

    The TRM and datasheet is trying to say we are compatible with JESD84-B51 for the data transfer modes listed in the timing section of the datasheet.

    The software driver will begin communications with the eMMC device assuming it is a legacy Multi-Media Card to determine its capabilities then change to a higher performance data transfer mode supported by both devices.

    Regards,
    Paul

  • 0 in reply to peaves
    Mastermind 9875 points

    Hi Paul,

    Thank you for your reply.
    I will share your response with my customer.

    Paul said:.
    It looks like portions of the TRM content was copied into the Detailed Descriptions chapter of the datasheet, where it makes the inappropriate association of host controller to the JESD84-B51 standard. I will need to discuss this with the TRM owner and have it fixed in the datasheet.

    I hope the above information will be reflected in the next datasheet.

    Best Regards,
    Kanae