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Object temperature sensing with TMP007EVM

Miriam Savage
Prodigy 80 points
Other Parts Discussed in Thread: TMP006

Hello,

I am trying to use a TMP007 evaluation module to sense the temperature of a cold glass vial. I have the evaluation software downloaded and this seems to be working well. When I place my hand in front of the sensor, I get a typical body temperature reading. However, when I place a cold glass vial filled with fluid in front of the sensor, room temperature remains being output. Same goes for chilled plastic and metal (~4 degrees Celsius). Do I have to change settings to obtain accurate values for these objects? Why would my hand give valid temperature output and other objects not? Is it possible the chip is damaged? I assumed it would be fairly straight forward to read temperatures with this eval module and software.

Thanks,

Miriam

  • 0
    TI__Mastermind 37740 points
    Hi Miriam,

    Just to let you know that I am still looking at this, and get back to you.

    Aaron
  • 0 in reply to Miriam Savage
    TI__Mastermind 37740 points

    Hi Miriam,

    My colleague posted the comment yesterday, but for some reason it didn't show here.

    Thanks for touching base with us. From what you have told us, I think you may be having a field of view issue. TMP006 and TMP007 average everything in it’s field of view. Your hand is a very large object when placed close to the sensor. So it takes up a large percentage of the FOV. On the other hand the vial is probably a smaller portion of the FOV therefore it is being averaged with the back ground.. You can do one or both of two things… #1 Put the vial closer to the sensor to take up a bigger portion of the FOV and use calibration procedures to calibrate the error out. #2 Restrict the FOV. We have done this using a tiny shield with a hole in it.

    Hope this helps. If you still have questions, please don’t hesitate to ask.

    Aaron

  • 0 in reply to Aaron Heng
    Prodigy 80 points

    Thanks Aaron. I had considered this and attempted to place the vial as close as possible to the sensor. I will look into a shield also.

    Regarding calibration - how would you advise doing this? Do I need an easycal board or can I figure out what values the coefficients should be at manually? I wonder if the chip needs to be tuned for the emissivity of glass?

    Miriam

  • 0 in reply to Miriam Savage
    TI__Mastermind 37740 points

    Hi Miriam,

    No problem, Miriam. We are here to help if you encounter any issue. The link below is the calibration guide that you may need to go through.

    Yes, the best tool is TMP007EasyCal EVM if you want to find the coefficient. You can get the board from this link .

    The TMP007 is sensitive to FOV and distance.  Therefore even when you put the device very close to the die, the round surface vs a flat surface will give you different distance.  Calibration will fix this, but the system will always be dependent on the fact that the vial is placed in the same location each time, or to say it a different way the placement of the vial needs to be repeatable.  

    The attached file is the FOV restriction lid that might be helpful to you.

    ThruHoleConcept.pptx

    Aaron

  • 0 in reply to Aaron Heng
    Prodigy 80 points

    Many thanks Aaron, this has been very helpful. 

    Regards, 

    Miriam

  • 0 in reply to Miriam Savage
    TI__Mastermind 37740 points
    Hi Miriam,

    I'm glad that we can help. I'll close this thread, but if you have any further question, please raise your concern again.

    Aaron