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Practical Sleep Modes

Victor44251
Intellectual 310 points

Other Parts Discussed in Thread: MSP430F5515

What's the most power efficient way to go into a low power mode (sleep) and be able to wake up periodically without any external event? Assume I have no responsibility during sleep mode besides staying asleep and waking up periodically. What is the current draw I expect while sleeping in this way? I'm using an MSP430F5515, but if there is some capability that a different MSP430 has for this type of operation I'd be interested in hearing that too.

  • 0
    Guru 58965 points

    You can go to LPM3 and use WDT or RTC sourced by VLO to wake it up. Current consumption is down to a few uA. See:

    "Low-Power Mode Supply Currents (Into VCC) Excluding External Current"

    on page 51 of the data-sheet SLAS590D –OCTOBER 2009–REVISED APRIL 2010

  • 0
    TI__Expert 5260 points

    In addition to OYC response, you can also divide the system clock down from the VLO.

    You can probably get to 500na or less with running from the VLO and a divided down system clock. I have boards running on my bench at 600nA, and that is running from an external 32khz crystal which requires some additiona currents.

    Brief summary:

    LPM3 + VLO + DIVIDED system clock = Lowest power mode and still have internal wake up. 

     

    -Jason

     

  • 0 in reply to Jason Kriek
    Intellectual 310 points

    @Jason,

    Thanks, that's kind of what I was hoping to hear, and it makes sense to me at a high level. Would you be willing to provide a minimal code example that achieves this current consumption during sleep and periodically wakes up to say toggle a pin, so that I might be able to independently verify your results?

    I would recommend posting the code to something like pastebin.com and providing a link to it here as the forum editor isn't the greatest for formatting code.

    Kind Regards,

    Vic

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