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More info about VBAT connection

stevesmythe

Dose anyone have any information about the VBAT connection and how it relates to a real-time clock? The documentation doesn't really explain it as far as I can see.

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    Steve

     

    The Real Time Clock (RTC) on the MT3620 Sphere device has an isolated power domain

    The default setting of J9 on the Starter Kit sets the power source of this RTC power to be from the main 3V3 power rail

    Moving the jumper to J9 pins 2 and 3, connects the VBAT connector to instead be the RTC power source (eg. power from an off-board coin-cell battery)

     

    Note: The MT3620 Azure Sphere RTC function:

    • Is controlled by the security subsystem in conjunction with the Azure Sphere operating system.
    • Can power-on the full chip based on a timer/time of day
    • Can power-on the full chip based on the WAKEUP input pin
    • Is count-down or sleep-time programmable for up to a year
    • If no power source is available via VBAT connector, the jumper must be fitted to J9 pins 1 and 2 (ie. connected to 3V3 rail), otherwise the device will not boot-up!

     

    -Peter