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AM2431: AM2431 - VDDSHV_SD_IO supply pins

MIKHAIL SALOV
Expert 6940 points
Part Number: AM2431

Good day Colleagues,

My customer is asking how to connect correctly pins CAP_VDDSHV_MMC (K15) and VDDSHV5 (L14/L15)?

EVMs schematics have these pins connected CAP_VDDSHV_MMC (K15) to VDDSHV_SD_IO and VDDSHV5 (pins L14/L15) didn't connect to VDDSHV_SD_IO.

The datasheet says CAP_VDDSHV_MMC pin should be connected to capacitor. VDDSHV5 pin should be connected to external power supply (1.8 and 3.3).

Thank you, Mikhail

  • 0
    TI__Guru 63125 points

    VDDSHV5 is the IO supply for pins associated with the MMC1 signal functions.

    You need to power the VDDSHV5 IO power rail from the internal SDIO_LDO if you plan to connect an SD Card to the MMC1 pins and you plan to support UHS-I SD Cards. UHS-I SD Cards begin communications with the host at their legacy IO voltage of 3.3V and change to 1.8V after the host has confirmed the attached card supports higher speed communications options.

    The internal SDIO_LDO will begin sourcing 3.3V to VDDSHV5 and change to 1.8V when appropriate. So SDIO-LDO is your VDDSHV5 IO power source in this use case.

    VDDSHV5 should be connected to a fixed 1.8V or 3.3V IO power source if the IOs associated with VDDSHV5 are not connected to a SD Card and used for their other multiplexed signal functions.

    Regards,
    Paul