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Some AM3352 PMIC questions

Stephen Thomas
Intellectual 710 points
Other Parts Discussed in Thread: TPS65910, AM3352

Hi,

I m trying to modify a circuit with AM3352 .The current design is being is having PMIC TPS65910 operating from a 5V supply

I would like to know if there is any problem in powering the PMIC from a 3.3V source ( buck regulator)? The  DC/DC converters inside PMIC  can operate from 2.7V

and the dropout is 250mV at max for some of the LDOs. Ive checked the reference design of TMDSSK3358_3H0009_REV1_2B_SCH but i think it is operating from 5V input.

So will it make my design inferior in anyways if 3.3V is used to power the PMIC..Or have anybody tested like this before?

Thanks ,

Regards

  • 0
    TI__Guru**** 393215 points
    Hi Stephen,
     
    Obviously you will have to use the external 3.3V power source to provide 3.3V to the processor in this case. This will need to be properly sequenced to the AM335X. See the AM335X Datasheet, Rev.F, section 4.1 for details of power-up and power-down sequencing.
  • 0 in reply to Biser Gatchev-XID
    Intellectual 710 points

    Thank you Biser  for pointing out that , i think the 3.3V you are mentioning is IO voltage power supplies right.? but is this recommended ? i.e powering from 3.3V external source direct with some sequencing manually.

    Also is there any other problems that can arise during operation ,if i some how manage the sequencing?

    Thanks.

  • 0 in reply to Stephen Thomas
    TI__Guru**** 393215 points
    Yes, 3.3V is used on I/O power rails. It shouldn't be a big problem to control it through a power switch. It should be sequenced from one of the PMIC supplies (you could use the one of the PMIC 3.3V LDO's to control the swich, in your case these LDO's will output lower voltage). There are a lot of power switches available. I don't think this usage will cause any problems in normal operation.
  • 0 in reply to Biser Gatchev-XID
    Intellectual 710 points

    Thank you Biser,

    I was checking the transient/dc load regulation characteristics of the PMIC ..Typically the load regulation is less than or equal to 100mV maximum.

    Just checking for any worst case scenario.

    Regards

    Stephen