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MSPM0G1507: VBAT Questions

MK
Intellectual 2145 points

Part Number: MSPM0G1507

Team,

 

1) For MSPM0G series (without Vbat) how does the MCU sure the RTC is always upto date even when the power is down?

2) In case we add an external RTC, should we add another voltage source? How is this external RTC connected to the MCU?

3) Is there any other way to connect the MCU RTC to an external battery( coin cell) to make sure it's retains the data?

Best Regards,

Mahdurya

  • 0
    Expert 1430 points

    The MSPM0G series has no VBAT pin. The RTC stops when power drops. It cannot keep time without a supply. You must restore time at boot.

    The simplest fix uses an external RTC. A DS3231 works well. It has its own VBAT pin. A coin cell powers it during outages. The RTC switches between VCC and VBAT automatically. The MCU reads the time over I²C. This approach is reliable and common.

    A good example is this project:
    https://www.pcbway.com/project/shareproject/Diy_RTC_Module_aef8ce7d.html
    It shows a DS3231 board with a coin cell. The design is clean and proven.