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RTC_C with AUXVCC3

Utthawut Bootdee
Prodigy 40 points

Other Parts Discussed in Thread: MSP430F6777

             I use MSP430F6777. The device-specific data sheet said "The RTC_C on this device operates on dedicated AUXVCC3 supply and supports operation in LPM3.5".

My MCU has three power supply domain,

                     1). DVCC (main from AC powersupply) connected to DVCC pin,

                     2). 3.6V-battery connected to AUXVCC1 pin

                     3). 3.0V-battery connected to AUXVCC2 and AUXVCC3.

              And also use hardware switching of the Auxiliary supply system module to handle these power supply domain. I have a question as below,

                     - If DVCC fails and both the AUXVCC1 and AUXVCC2 are lower than the selected threshold voltage (AUX1LVLx and AUX2LVLx).

                                1). Now, MCU should be turn-off due to none of supply domain for switching, right?

                                2). Can RTC_C operate in calendar mode with AUXVCC3 while MCU turn-off? If it can operate, what is going on when the DVCC returns?

                                3). Can I connect AUXVCC3 pin to VDSYS pin?

  • 0
    Guru 227245 points

    I don't have an answer for your questions, as I never worked with the AUX module.
    But I remember that the RTC will always work from AUXVCC1 (?) as well as the XT1 crystal. Without AUXVCC1, even if DVCC is there, neither XT1 nor RTC will work.

    But there have been some threads about this. Use the board search function to locate them. I dimly remember that at least a few of your questions have been discussed there.

    And as a side effect, my answer pushes your thread in front :)

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