How to improve resolution of Max6675

Discussion in 'General Electronics Chat' started by urb-nurd, May 22, 2015.

  1. urb-nurd

    Thread Starter Member

    Jul 9, 2014
    269
    3
    My friend is using a MAX6675 thermocouple amplifier but is complaining of a drift error in his output over time.
    (12-bit output representing up to 1024 Celsius)

    I checked the datasheet and it states an expected error of around 4-8 LSB's which amounts to 1-2 Celsius given the resolution.

    I was wondering how you could go about reducing the usable input range to the amplifier to ensure that the 12-bit output represents 0-300 celsius (his useable temperature range) which would improve the resolution to 0.07 c and minimize the effect of this error.

    Any other solutions are welcome!

    Thanks AAC
     
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    How is the thermal bond between the chip and the input terminals done?
    Can you show your schematic and some pictures of the device?
     
  3. urb-nurd

    Thread Starter Member

    Jul 9, 2014
    269
    3
    Its actually a friend of mine from another forum, i am not sure about the thermal bond between the chip and input terminals, but given the datasheet information and resolution they match his errors.
    So my question is how to reduce the input range to improve the output resolution.
    THanks
     
  4. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    I don´t think that it is possible to change the range. You could try getting some other better suited chip.
     
  5. urb-nurd

    Thread Starter Member

    Jul 9, 2014
    269
    3
    i Though that may be the case!
    Thanks
     
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