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AM2434: MMC CAP_VDDSHV_MMC1

Lawrence Wong
Genius 15760 points
Part Number: AM2434

Customer designing board.  As given in schematic checklist, CAP_VDDSHV_MMC1 need 3.3uF. What is tolerance of capacitance put on CAP_VDDSHV_MMC1?? could it be 4.7uF? Is 2.2uF+1uF ok instead?

  • 0
    TI__Mastermind 18470 points

    Hi Lawrence, 

    For that particular capacitor, we recommend using a nominal 3.3uF capacitor. That pin is feeding an on-die LDO. The feedback stability analysis on that supply is done based around the 3.3uF nominal value. Also, if starting with too small of a cap, over time with aging, that might degrade the performance of the LDO. Please use the recommended 3.3uF.

    This is in contrast to the normal decoupling on the core, IO and clock power nets where substitutions can be made from our initial recommendations as long as the overall resulting PDN transient response is still sufficient. 

    Thank you,

    -Randy

  • 0 in reply to Randy Rosales
    TI__Genius 15760 points

    Hi Randy,

    is it ok to use 2.2uF +1uF?  Issue is 3.3uF are difficult to source

    Regards,

    Lawrence

  • +1 in reply to Lawrence Wong
    TI__Mastermind 18470 points

    Hi Lawrence, 

    I think that would be fine. Just make sure to mount them right next to each other in the layout. 

    Thank you,

    -Randy