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AM2431: 1.8V power supply

futoshi kawarazaki
Prodigy 165 points
Part Number: AM2431
Other Parts Discussed in Thread: TPS65219, LP8733

I am looking at the AM2431 datasheet(SPRSP65F).
The AM2431 datasheet states "The LP8733 or TPS65219 Power Management IC (PMIC) is recommended for an integrated power solution." in 9.1.1.1 Power Supply Designs.
Due to our circumstances, we are unable to use LP8733.
We plan to use TPS62824ADMQR.
The 1.8V of the LP8733 is not a switching regulator, but an LDO.
Does the 1.8V supply of the AM2431 need to be LDO?
Would the 1.8V supply of the AM2431 be concerned about ripple noise?

  • 0
    TI__Mastermind 22835 points

    Hi,

    The Recommended Operating Conditions spec for the power supplies includes all margin/tolerance allowed on the power rails.  This includes ripple noise as well as margin for power supply variance.  It is up to you to decide how you want to break this up, but a common strategy is to allow 50% of the margin for DC margin (power supply variance) and 50% of the margin for AC/ripple noise.

    Since the 1.8V rails on the AM243x are +/-5%, a 50/50 split would be 2.5% allowed for DC margin and 2.5% for AC/ripple noise.  Using this approach, the maximum AC/ripple would be 45mV.

    However, these percentages can be tweaked based on your design/application, so 50/50 is not a hard rule, just a recommendation for an initial approach.

    Thanks,
    Mike

  • 0 in reply to Mike Pridgen
    Prodigy 165 points

    Hi
    I appreciate your assistance in resolving the problems.
    Thanks