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TMP007: calibration process setup - how to create the excel file

Tal Bareket25
Prodigy 175 points
Part Number: TMP007
Other Parts Discussed in Thread: TMP116

Hi

in my application, both die and object temprature vary.

the limits are known and defined ( 15 to 35 deg ), the application is medical, an acccuracy of < 0.5 Deg is required.

sidtance from sensor ~ 6 mm.

I do not fully understand how exactly to make the tests needed to achieve the data for calibration ?

what I mean is for the exact test for calibration - how it should be done ? 

for instanse - let me define the calibration test setup:

1. initially - the TMP007 sensor is at room temprature ~ 25Deg 

2. the sample object is heated to 40 deg in a special oven ( more than the upper limit )

3. sample object is put in actual position ( ~ 6mm away from TMP007 sensor)

now - both the die temprature  and the object estimated temprature increases instantly to ~ 40 deg 

4. start the data collecting, by using 1Sec integration time of the TMP007 sensor.

during data collection - the sample object temprature drops down to aroud the room temp.

first question - can this test be accounted to cover both  T die and T object high range ( meaning - from room to upper limit temperature )  from calibration data requirements point of view ?

5. now - in order to cover the lower range (meaning lower limit to room temperature range ) , the set up cools down by external means

6. the data collection will continue until the system will reach a few degrees below the lower limit.

 second question - can this test be accounted to cover both  T die and T object  low range ( meaning - from room to lower limit temperature )  from calibration data requirements point of view ?

I do hope all the data I provided is clear, since we are not having a conference call, but writing this down.

thanks

Tal

  • 0
    TI__Expert 5695 points
    TI Support team will contact you shortly.
  • 0
    TI__Mastermind 35895 points
    Normally, a Black Body Calibrator is used as an infrared temperature source in a lab environment. You can see various models in a web search. This device has a black plate with a near-ideal emissivity, and a regulated temperature control for the plate. The instrument can be configured for various temperature set points, and you would collect your data in this stabilized environment.

    If your experiment closely emulates your application, then you may as well use a local temperature sensor without infrared thermopile. I say this because of your comment that die temperature quickly reaches object temperature. This happens because the object is very close to the sensor, and is able to heat it quickly via convection heating. For your medical application, I recommend TMP116.

    Ren
  • 0
    TI__Prodigy 355 points

    Hello Tal.

    Reading your question I thought that part of following calibration instruction can be useful to you:

    The TMP007 Calibration Procedure

    The standard TMP007 calibration procedure usually consists of the following steps:

    1. After setting the environment parameters like distance to object, device orientation, supply voltage, data sampling rate and etc, the user should specify the object and device temperature data range. The rule of thumb is: the narrower are temperature ranges the more precise object temperature measurements will be.  Also the limited ranges give more chances that common coefficients will provide acceptable precision for all parts and individual part calibration can be excluded.

    2. At this step the calibration points should be chosen. The one calibration point is a combination of a die and object temperatures. Here is assumed that user can control the die and object temperature during the calibration or at least measure an object real temperature during the calibration process. The rules how to choose the calibration points will be described latter.

    3. Collecting the calibration data. For every calibration point when die and object temperature are stabilized the user collects three parameters: the die local temperature read from the device, the TMP007 IR sensor voltage reading and the measured object real temperature obtained from an external thermometer. For better precision it is recommended to use 10-30 readings average. If goal is to obtain a common coefficients which latter will be used for many parts, than 5-10 parts averaged calibration data should be used.

    4. Calculating and adjusting the coefficients. The calibration data should be put in *.CSV file and loaded into the TMP007_Coef_Calculator program. Using auto and manual mode user finds the best coefficients combination and save it in output *.csv file.

    5. The founded coefficients are loaded into TMP007 device and measurements are repeated for calibration points. This time the measured object temperature is read from the device register and is compared with the object real temperature. If the measured object temperature error is in an acceptable range than calibration is done and coefficient values can be stored in TMP007 nonvolatile memory. If error is too big than error sources should be analyzed. The most common source of errors is an air flow inside the system or significant die temperature change during the measurements. After system adjusting the calibration procedure should be repeated.

    Choosing the calibration points

    When the local and object temperature ranges are set it is a time to choose a calibration points.  Usually the measurement area is a rectangle box and a standard way to locate the calibration points are the box center, box corners and the box side centers. Together it gives us 9 points.

    On fig.1. Is shown the example of calibration points set for Tdie range +25C…+75C and object range +25C…+100C

    Fig 1. Example of choosing calibration points for Tdie range +25C…+75C and object range +25C…+100C

    When you collected the calibration data, then you need to use a program which calculates the coefficients for you. Contact me if you are interested and I'll provide it to you

    Regards,

    Michael

    Michael_Gurevich@ti.com

  • 0 in reply to Mihail Gurevitch
    Prodigy 175 points

    Hi Michael

    Thank you very much for replying,

    Please be noted I have carefully read all TI relevant document available in TI site.

    although there is much formal documentation on site - there are some issues un clear to me.

    the fact that I can not talk to a person on phone and close all my questions, is a big issue for me.

    to get to the point -

    this does not address my need.

    Could you please advise the following -

    how to I calibrate more than one test ? assume all the die and object matricx can not be achieved in a single test, how shall I calibrate this data?

    any chance to have a short technical call on this ?

    I am located in Israel, my Email is tal@clrcut.comI will appriciate if you can find 10 minutes of your time to talk to me, if this is possible for you.

    thanks\

    Tal Bareket 

  • 0 in reply to Tal Bareket25
    TI__Expert 5695 points
    Customer and TI team closed the remaining actions using email due to the nature of information shared.