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TMP007 IR Sensor

DAN ROSS1
Intellectual 670 points

Hello.

I've been using the TMP007 now for about a year and have noticed there seems to be a large accuracy error until the sensor has been powered up for 5 - 10 minutes, allowing Tdie to adjust to room temperature. I'm not allowing any IR energy to be detected by the sensor as it's in a flat black small container that's sealed for this test. Just strictly reading Tdie, Tobj, & status register.

With that said, I guess it makes sense as with no IR energy, Tobj & Tdie should be equal (or very, very close to equal). I'm wondering if calibrating the sensor is going to have any effect on this or not (don't see how). Should I just plan on keeping the sensor powered at all times and just give it the software power down command when not in use?

Thanks

Dan Ross - AST

  • 0
    TI__Genius 15760 points

    Hi Dan,

    Thank you for using TI E2E Forums. Your question was in a different forum group, the sensing group received your question just today. Please allow us some time to review your questions. 

    Mayrim

  • 0 in reply to Mayrim Verdejo
    Intellectual 670 points
    I just realized I left out part of the description!! As posted, with no IR energy being detected, Tobj = Tdie (or very close). The question is after the sensor has been without power all night and with the heat turned down, Tdie is lower by approx. 5 degrees F. The sensor is then uncapped allowing IR energy to the sensor. The target object is at a known temperature of 72 degrees F. However, the object temperature I'm reading appears to be following Tdie.

    That is, in the morning, Tobj = 67 degrees F. After approx. 10 minutes of being powered, Tobj = 72.4 degrees F. The sensor has not been calibrated and I'm wondering if calibrating it is going to adjust for this.
  • 0 in reply to DAN ROSS1
    TI__Intellectual 1811 points

    Dan, 

       Thanks for the post.  It sounds like you are describing a turn on drift.  I went to the lab and tried to check out the turn on behavior.   I do see about 4 reads at one read a second after turning the device on, but nothing like 5 minutes. Is there any chance that this is a system warm-up that you are seeing. If that is the case then Calibration would help. We have a new tool. TMP007EasyCalEVM. It provides a reference chip to attach to your object. Then calculates coefficients base on the data it records. One thing to keep in mind about calibration. The calibration is only as good as the data extremes you are able to gather data at. For example, If I calibrate for an object temp from 60F to 80F and Tdie 68F to 75F your numbers will be very good in this range but outside this range you will get larger errors.   I say this because a lot of times being able to change the tdie is a challenge. You want to let the system change this for you, not artificially changing it with an outside source. Blowing a hair dryer on it isn’t going to get real good results…

       Hope this helps. Let me know if there is anything else we can do to help.

     

    Regards,

    Tommy Santoyo

    Sensing Apps Team