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TMP006/007 - How to "shield" part from ambient heat and how to know when to recalibrate?

We are currently prototyping with the TMP007. The application involves "looking" down on the target object from above, and in certain conditions, heat from the target object will actually cause die temperature to rise several degrees. So, two questions:

1) Any ideas on ways to "shield" the part from this heat without "blocking" the thermopile's "view" of the target object (unfortunately, heat rises and the orientation of the sensor and the target object can't easily be changed)?

2) I get some very erratic temperature readings when the die temperature rises a few degrees C (which is expected). I assume that the right course of action would be to recalibrate at the new temperature (or at least load a new set of coefficients pre-calculated for the higher temperature), but how do I know when this is necessary? For example, what would tell me that the temperature could no longer be relied on? Or is the recalibration "trigger" just based on a certain percentage change in the die temperature?

--Eric

  • Hi Eric,

    We will get back to you soon.

    Mayrim
  • Eric,

       Thanks for contacting us.   I've done a lot of work with shields on the TMP007 and TMP006.   We have worked with shields for basically two reasons, first to reduce the field of view, and second to reduce air effects.  Please see the picture below.  I don't know if something like this is acceptable for your project but it could help.  I have samples of this shield that I can share.

    Regarding the re-calibration.  The best approach is to calibrate the part at  die and object extremes.   Basically if  you can gather data  form lowest  to highest expected die temp, and lowest to highest expected object temp. You can use this data to create coefficients that will work anywhere in the range.  You will need 3 sets of data.  uV out at each temp, local "die" temp, and actual measured object temp.  Sometimes that's easier said than done, but that's the best approach.

    Please let me know if there is anything else i can do to help you prototype process.

    Regards,

    Tommy Santoyo

    MHRS Sensing Apps

  • Thank you for the quick and detailed response.

    Yes, I would be interested in a sample of your shield. What is the hole diameter? Please send me a private email and I'll provide you with shipping information.

    Regarding the calibration, are you saying that with the right set of coefficients, I should expect the device to report accurate target measurements over a range of die temperatures? That would be great if so. Can you provide an example of the data and the calculation needed? BTW, I have an EasyCal EVM on the way.

    --Eric

  • Eric,
    Regarding the shield. The standard one I have samples of, has a 1mm hole. The great news is that the TMP007Easy Cal you ordered can accomodate one of these shields. Email me your shipping address and i'll get you samples.  
    Regarding the calibration, yes with proper calibration i expect one set of coefficients will work.
    Regards,Tommy SantoyoMHRS Sensing Apps Team