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SB_S's avatar
SB_S
Icon for New Contributor rankNew Contributor
6 years ago

SD card and eMMC Transceivers for 1.8V

Do we need to have transceivers if we support 1.8V IO level on FPGA ? Doesn't have the capability to support the 1.8V ?

And also it requires the PU to 3.3V on these interface. ​Are these mandatory ?

6 Replies

  • SB_S's avatar
    SB_S
    Icon for New Contributor rankNew Contributor
    6 years ago

    ​Yes , question is referred to SD/MMC and eMMC Card Interface Design.

    In the above table , for 1.8V SD/MMC Flash memory needs external transceiver . What does it mean ?

  • EBERLAZARE_I_Intel's avatar
    EBERLAZARE_I_Intel
    Icon for Regular Contributor rankRegular Contributor
    6 years ago

    I see, well since the HPS I/O use a fixed voltage level and cannot be changed dynamically, transceivers are required to support level-shifting and isolation for cards that can operate at 1.8 V.

    The SD/MMC cards support various operating voltages, for example 1.8V and 3.0V. If you have a card which is at 1.8V and you eject it and replace it with another card, which is 3.0V, then voltage switching is required. Many SD cards have an option to signal at 1.8 or 3.0 V, however the initial power-up voltage requirement is 3.0V. To support these different voltage requirements, external transceivers are needed.

    More information here on page 1721 (Flow Diagram).

    Regards.

    • SB_S's avatar
      SB_S
      Icon for New Contributor rankNew Contributor
      6 years ago

      ​So for eMMC this trancievers are not required right ? because this voltage doesn't change as SD card . So 1.8V emmc device should work .

      • EBERLAZARE_I_Intel's avatar
        EBERLAZARE_I_Intel
        Icon for Regular Contributor rankRegular Contributor
        6 years ago

        Hi,

        If the operating voltages are both 1.8V as mentioned, external transceiver are not required.

        Regards.