Digital potentiometer between +/- 2.5V

Discussion in 'General Electronics Chat' started by atferrari, Apr 30, 2011.

  1. atferrari

    Thread Starter AAC Fanatic!

    Jan 6, 2004
    2,644
    759
    My previous experience with digital potentiometers is only using them as voltage dividers with one end to ground but this time I intend to replace Rf1 in the attached circuit (filter) using a 100K digital potentiometer in rheostat mode.

    Just in case I verified that both ends are at 0V DC.

    To accommodate a signal of 4V pk-pk, I should provide a dual supply of +/- 2.5V to the digipot.

    My question: is it any simple way to ensure that the micro in charge (working between +5 and 0V) can communicate with the IC without damaging it?
     
  2. ifixit

    Distinguished Member

    Nov 20, 2008
    638
    108
    Hi,

    The end of Rf1 going to the - input is a virtual ground. However, failure modes and start-up conditions could cause either end to be at ±15V.

    Choose a part that has at least a ±15V supply range to be safe. The digital control inputs should have a separate logic supply (5V) and is not effected by voltages on the resistor.

    What is the digital pots part number?

    Regards,
    Ifixit
     
  3. atferrari

    Thread Starter AAC Fanatic!

    Jan 6, 2004
    2,644
    759
    Found a much simpler solution: moving all non inverting inputs to +2,5 V. The digipots will be centered in the middle.

    Thanks for your time.
     
Loading...