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AM6442: Where to find the source of VDDSHV_SD_IO signal on AM6442 EVM ?

Denny%20Yang99373
Expert 3805 points
Part Number: AM6442

Hi all,

VDDSHV_SD_IO used for VDDSHV5 and SD card power supply, but I can't find the source of VDDSHV_SD_IO?

Is there any mistake on EVM design?

If I don't want used SD card, how to process CAP_VDDSHV_MMC1? Left unconnected or connect to ground with a capacitor?

thanks!

BR,
Denny

  • 0
    TI__Genius 13505 points

    Hi Denny,

    VDDSHV_SD_IO is sourced by CAP_VDDSHV_MMC1 through an internal dual-voltage output LDO (3V3 or 1V8), supplied by VDDA_3P3_SDIO.

    CAP_VDDSHV_MMC1 needs to be always bypassed to gnd with 1uF cap per the datasheet.

    Regards,
    Mike

  • 0 in reply to Michael Erdahl
    Prodigy 80 points

    Can I power supply for VDDSHV5 without using internal LDO(CAP_VDDSHV_MMC1)? It's just powered from an external source.

    I find that CAP_VDDSHV_MMC1 needs to be always bypassed to gnd with 3.3uF cap not 1uF cap from datasheet, Please confirm it.

  • 0 in reply to jianwu wan
    TI__Genius 13505 points

    Hi Denny,

    Thank you for your patience - I will reply regarding your question about bypassing the internal LDO.  You are correct about the capacitor - it was my mistake.

    Regards,
    Mike

  • 0 in reply to Michael Erdahl
    TI__Genius 13505 points

    Denny,

    Yes, you can supply VDDSHV5 without using the internal LDO.

    I will explain how the device operates since it is not clear from what I've been able to read in the datasheet and TRM.  The SDIO LDO input is VDDA_3P3_SDIO.  The MMC controller will automatically set the IO voltage based on the mode (1.8V or 3.3V).  This LDO output is taken from the CAP_VDDSHV_MMC1 pin, and routed to VDDSHV5, which powers the MMC1 I/O voltage domain.

    Regards,
    Mike