Efficient Implementation for a Maximum Voltage Finder

Discussion in 'Analog & Mixed-Signal Design' started by omh11, Aug 1, 2018.

  1. omh11

    Thread Starter New Member

    Apr 13, 2011
    2
    0
    I am trying to find/design a circuit that finds the maximum voltage from multiple inputs. I found a patent US6,188,251B1 that describes something similar, but I am wondering if there are any off-the-shelf IC out there that do what I need? I figure if designing a circuit using regular op amps the circuit would become huge as the number of inputs (and thus outputs) increase.
     
  2. Kjeldgaard

    Member

    Apr 7, 2016
    264
    95
    An analogous solution could look like this:
    FindMax_1.jpg

    The above should only be seen as a sketch of the very first idea I got.
     
  3. omh11

    Thread Starter New Member

    Apr 13, 2011
    2
    0
    Great, thanks!
     
  4. Sensacell

    Moderator

    Jun 19, 2012
    1,868
    559
    This should work, might "chatter" a bit when voltages are near each other.
    one_of_Many.png
     
    Kjeldgaard likes this.
  5. danadak

    Well-Known Member

    Mar 10, 2018
    1,252
    257
    One chip, 48 channels. I did not spend the time to see if there was a bigger package
    to get to 64 channels, but I think there is one. The SAR is 12 bits. May be able to
    do this with its DelSig for 16 - 20 bits.

    SAR channel sample rate is 100K SPS, sample rate of all 48 channels is ~ 2K SPS.

    If V's are > 5V you would need R dividers at each input.

    upload_2018-8-1_8-20-29.png

    Note I did not add other resources (which are on chip) for LCD interface, COMM,
    timers,counters, PWMs.....blah blah blah (see attached component list). A component
    is an onchip resource.

    PSOC Creator is free tool - http://www.cypress.com/products/psoc-creator-integrated-design-environment-ide

    Board to start with $ 10 (This does not have enough I/O pinned out to do all
    channels, you would need to do your own PCB layout). You can use the board
    to debug basic approach, write code, etc.. Then scale the settings to do a chip
    and program to place on PCB to do all channels.

    http://www.cypress.com/documentatio...oc-5lp-prototyping-kit-onboard-programmer-and



    Regards, Dana.
     
    Last edited: Aug 1, 2018
  6. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    8,489
    1,925
    What voltage range and how accurate a maximum?
     
  7. kubeek

    Expert

    Sep 20, 2005
    5,221
    976
    Do you only need to know the maximum voltage, or also which of the inputs has that?
     
  8. crutschow

    Expert

    Mar 14, 2008
    19,378
    5,398
    What's the maximum number of inputs you need?
     
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