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Original question:

AM3352: RTC timer questions

LAUNCHXL-CC1310: How to power on AON_VD via a secondary battery source?

Chan100
Genius 3040 points
Part Number: LAUNCHXL-CC1310
Other Parts Discussed in Thread: TPS22910A

Hi everyone,

I am working with LAUNCHXL-CC1310. For our application, we would need the RTC on board running all the time. Generally the board is powered on via a DC power supply. However the user can decide to turn it off and hence the RTC under AON_VD power domain would turn off. We require it to be on and hence plan to install a secondary battery source such as a coin cell battery to power on only AON_VD domain or, if possible, only RTC.

So my question is what can be the starting point for this? Can anyone please suggest?

Thanks in advance,

-Chandrasekhar DVS

  • 0
    TI__Guru**** 317180 points

    As PER the datasheet, it's not possible to just power one power domain.

    I would assume that you have to place the secondary battery in parallel with the DC supply.

  • 0 in reply to TER
    Genius 3040 points

    Hi TER,

                We are also looking for the solution on our custom board for this problem based on LAUNCHXL-CC1310. The voltage given by the primary supply is different than what we would like to install for the secondary source. So keeping them in parallel is off. We cannot install another regulator only for this reason due to cost issues. So is there no other way to achieve this?

  • 0 in reply to Chan100
    Genius 3790 points

    Hi,

     you can consider one of the  Load Switch With Controlled Turn-on (like  TPS22910A) as an option.

    As Primary and secondary source  Voltage range is unknown, It's hard to suggest.

    What'll be your secondary source? A coin cell?

    Make sure input to the uC will be within the range of 1.8V-4.1V(Abs. Max).

    I'd suggest you to go through below link to PowerMux, which might be useful to you.

    http://www.ti.com/lit/an/slvae51/slvae51.pdf

    Thanks.

    Lakshminarayana.

  • 0 in reply to Lakshminarayana
    Genius 3040 points

    Hi Lakshminarayana, thanks for the suggestion, this seems good. I will look into that.

    -Chandrasekhar DVS