AM3352: VDDS_RTC power sequence with external buck

paddu2017

Part Number: AM3352
Other Parts Discussed in Thread: TPS65910

Hi,

We need confirmation about the power-up sequence of AM335x+TPS65910.
As per the user guide, when using TPS65910AA1/TPS65910A3A1, an external buck
should be used to power VDDS_RTC.

When using external buck for VDDS_RTC can we ramp VDDS_RTC independent of other power supplies?
As per the AM335x Power-up sequence, the Sequencing Order for VDDS_RTC is "1".
So,should we select external buck that would match the Power-up sequence and ramp early than other power supplies?

Our application won't use RTC feature or PMIC_PWR_EN functionality.

Best Regards
Paddu

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

Please see the AM335x GP EVM schematic: processors.wiki.ti.com/.../AM335x_General_Purpose_EVM_Board_Design_Files On page 5 you will find U5, which is the external VDDS_RTC power supply.

0 paddu2017 over 8 years ago in reply to Biser Gatchev-XID

Expert 2885 points

Hi Biser,

Thank you.

Yes,I have seen that both EVM and Starterkit uses TPS71718 as an external supply for VDDS_RTC.
But,what if we choose different solution.

Should we ramp external supply(VDDS_RTC) first and other supply later?
or is it OK to ramp VDDS_RTC independent of other power supplies?

Best Regards
Paddu

0 Biser Gatchev-XID over 8 years ago in reply to paddu2017

TI__Guru**** 393215 points

Per AM335x Datasheet VDDS_RTC should always be ramped-up first.

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AM3352: VDDS_RTC power sequence with external buck