Digital Potentiometers Operating with no Power

Discussion in 'Embedded Systems and Microcontrollers' started by dannybeckett, Dec 16, 2014.

  1. dannybeckett

    Thread Starter Active Member

    Dec 9, 2009
    163
    0
    Hello fellow electronic enthusiasts!

    Is there such a thing as a non-volatile digital potentiometer that will operate as usual when the power is removed from it? The application is for a deep sleep circuit with a calibration potentiometer that essentially governs when the system comes back out of sleep. The value of the pot won't be changed during deep sleep, but it does need to operate. Worst case, I'll use a low quiescent digipot that will have constant power, best case there's a device out there that will still behave properly when the power is removed.

    If there isn't, are there any low quiescent, low voltage (direct lipo power, ~2.5V to ~3.7V), SPI controlled digipots out there that anyone could recommend?

    Cheers for your help guys,

    Dan
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,447
    3,363
    Yes. Digital pots are non-volatile. They retain their position in EEPROM while not being powered.
     
  3. dannybeckett

    Thread Starter Active Member

    Dec 9, 2009
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    I was aware that non-volatile digipots will power back online with the same value they powered down at, but are you sure they will continue to operate properly when the power is removed?
     
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,392
    1,606
    That is a negative.
     
    dannybeckett likes this.
  5. JWHassler

    Member

    Sep 25, 2013
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    I'm pretty sure they won't. They wouldn't have power pins if they didn't need them.

    Does your microprocessor have a low-frequency oscillator that you can use to run a timer?
    For instance, a Freescale RS08 will use approx 1.5uA in 'stop'-mode, running a 1Khz timer.
    Many other processors have similar 'sleep'-provisions.
     
  6. dannybeckett

    Thread Starter Active Member

    Dec 9, 2009
    163
    0
    This design I'm working on is rather unique in so far as I have some very low quiescent analogue circuitry that actually sends power to the microcontroller when brought back out of sleep. The micro has absolutely no power otherwise. The same goes for the digital circuitry, zero power until the analogue side says so.

    I've found a chip that draws 2.5uA (typ) @ 5.5V whilst the serial side is quiet, this will be fine for my purposes. Cheers for the help guys.
     
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