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TMP006 sample error

Adel Moadi
Prodigy 160 points
Other Parts Discussed in Thread: TMP006

Hi

I'm working on a project using TMP006 to measure human skin temperature.

when I measure the temperature with the  tmp006evm  board, i get  a very different result from what i get with the component assembled  in my own board under the same conditions.

the value for temperature is  28, i receive with the tmp006evm  board registers via the GUI:

tdie = 0xE20

vobj = 0xFF35

and my own board shows 

tdie = 0x102C

vobj = 0xFBCC

Note: the TMP006 sensor soldiered in rework machine for BGA IC's 

the difference in the setup between the  tmp006evm  board and mo own board is :

1)  the power supply for the tmp006evm is 3.3V and my own board is 5V.

Can someone tell me the reason why it happened ?

Best Regards

Adel

  • 0
    TI__Expert 7945 points

    Hello Adel,

    There is a lot of variation in Tdie between the EVM and your setup. Let me ask you a quick question..

    Did you follow the lay out guidelines listed in the user guide document located at http://www.ti.com/lit/ug/sbou107/sbou107.pdf  when you designed your board?

    Regards,

    Abhi

  • 0 in reply to Abhishek Muppiri
    Prodigy 160 points

    Hello Abhi

    yes, the board designed according to sbou107 guide document.

    Regards,

    Adel


  • 0 in reply to Adel Moadi
    Prodigy 160 points

    Hello Abhi

    yes, the board designed according to sbou107 guide document.

    i get the the first version design board before 2 weeks,

    now i  check if the sensor is working well (functionality and accuracy) in my project .

    Regards,

    Adel

  • 0 in reply to Adel Moadi
    TI__Expert 7945 points

    Hello Adel,

    It's good to know that you have followed the recommended layout guidelines mentioned in the users guide document. Now to answer your previous question, Yes you will see a shift in the binary value equivalent of temperature when you increase the voltage from 3.3 to 5V. You will note that this will be a constant offset value across different temperatures for your 5V board compared to 3.3V EVM board. Hope I answered your query.

    Regards,

    Abhi

  • 0 in reply to Abhishek Muppiri
    Prodigy 160 points

    Hello Abhi

    Thank you for your response, it helps me a lot but it still doesn't solve the whole problems.

    I need to know how the supply voltage changes the device offset, can you provide me a conversion table or graph showing me the relationship between the voltage and offset value?

    In the case this table is available which is the dispersion from device to device?

    From the datasheets we see the voltage increase/decrease is about 7 ìV/°C , this is a typical value for TA = +25°C, V+ = 3.3 V, 

    Is this value affected by supply voltage change? or in other words does the temperature amplifier gain also change with supply voltage?

    Regards

    Adel

     

  • 0 in reply to Adel Moadi
    TI__Expert 7945 points

    Hello Adel,

    I'm working on your question your question. I will get back to you with the details soon.

    Best Regards,

    Abhi

  • 0 in reply to Adel Moadi
    TI__Expert 7945 points

    Hello Adel,

    Let me answer your questions.....

    I need to know how the supply voltage changes the device offset, can you provide me a conversion table or graph showing me the relationship between the voltage and offset value?

    Following graph graph does over the relation ship between offset voltage with respect to supply voltage. This graph is part of our characterization results for 10 parts. You can also observe the drift from part to part here.

    For every 1°C change in the temperature there will be 10uV change in sensor voltage.

    In the case this table is available which is the dispersion from device to device?

    Dispersion from device to device increases upon increase in voltage from part to part. See graph above 

    From the datasheets we see the voltage increase/decrease is about 7 ìV/°C , this is a typical value for TA = +25°C, V+ = 3.3 V, 

    Its ~10uV/°C

    Is this value affected by supply voltage change?or in other words does the temperature amplifier gain also change with supply voltage?

    temperature amplifier gain does not change with supply voltage.

    I would like to know your intended application so I can better service your needs. 


    Best Regards,

    Abhi