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TPS65217C with AM3352 does not support RTC-only mode?

LeonardEllis
Guru 71536 points
Other Parts Discussed in Thread: TPS65217

My question is similar to the previous post: https://e2e.ti.com/support/power_management/pmu/f/200/p/536229/1956206#1956206 .  Feedback from a schematic/design review stated the following:

The TPS65217C doesn’t support RTC-only mode because LDO1 (which is “Always-On” LDO) used to supply VDDS and VDDS_RTC power domain together. In this case if you power-OFF PMIC VDDS power domain stays powered.

And I don't understand how the 'power domain' remains powered if the PMIC is not supplied power?

~Leonard   

  • 0
    TI__Genius 10885 points

    Hi Leonard,

    Powering off the PMIC and removing power from the PMIC can be considered two different conditions.

    • The Always-On LDO will not be able to regulate if power is removed from the PMIC. This would mean VDDS_RTC can't be supplied as well.
    • The PMIC can be turned off (disable all regulators) using the PWR_EN pin, and as long as the input supply is still active the Always-On LDO can still regulate. If this LDO is supplying VDDS, that "power domain" will remain powered.
    • RTC-Only mode of the AMM335x states "All power supplies are OFF except VDDS_RTC," and this cannot be accomplished when VDDS and VDDS_RTC are shorted to the same LDO.