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MSP430G2955: Order of power supply sequencing

Doug Broadwell85
Intellectual 440 points
Part Number: MSP430G2955

Tool/software:

Are there any constraints on the sequencing of the power supplies:  DVcc, AVcc, REF+ ?

Thanks, Doug

  • 0
    TI__Prodigy 320 points

    Hi Doug,

    First of all, I would like to know if you run into problems on these power-up sequencing. Since there are no specific requirements on the MSP430G2955 datasheet, it is recommended to follow the normal power-up sequence. 

    Here are some suggestions：

    1. We recommend powering the AVCC, DVCC pins from the same source.

    2. Generally, DVCC should be powered up first to complete the initialization of the microcontroller peripherals. AVCC (analog power supply) can be powered up simultaneously with DVCC or shortly after DVCC has stabilized. If Vref is an internal reference voltage, it will automatically activate once both DVCC and AVCC are stable. If Vref is an external reference voltage, ensure it is powered up after AVCC has stabilized, or at least at the same time as AVCC, to avoid loading an unstable reference voltage while AVCC is still settling.

    Best Regards,

    Peter

  • 0 in reply to Peter Jiang
    Intellectual 440 points

    Hello Peter,

    The problem we're having is CPU's failing in the field.

    From what you've said, it looks like all 3 supplies need to come up at the same time, or else in the order DVcc, AVcc, Vref.

    Thanks

  • 0 in reply to Doug Broadwell85
    Guru 21925 points

    An external Vref gets applied to a pin which, like all of the GPIO pins, has diode clamps. So the absolute maximum limit very much applies. If the voltage exceeds DVcc then the diode clamp turns on. Diverting power from Vref to DVcc and likely providing sufficient power to run the CPU. This can cause trouble. Such as preventing cycling DVcc from resetting the CPU.

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