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TMP1075: How to calculate the response time of TI temp sensors?

Zhizhao Niu
Expert 3025 points
Part Number: TMP1075
Other Parts Discussed in Thread: TMP461, LMT86, TMP126,

Dear team, 

We receive a question about how to calcualte the response time of the TI temp sensor. Such as TMP1075, TMP461, TMP126 and LMT86? From my understanding, the responsible time should be from the real temp change time point to the data send out to the host for digital temp sensor. For the analog temp sensor, the response time should be when the temp change to the output voltage change. Could you please share your comments on how to calculate such data by the spec shown on the datasheet? Thanks. 

I attach a example from thermistors response time spec for reference.

B.R.

Lucas

  • 0
    TI__Expert 7795 points

    Hi Lucas,

    Thermal response is measured by taking the device from room temperature (T1 = 25C) and then submerged into a galden oil bath (stirred liquid at T2 = 125C) or temperature chamber (still air = 70C) as noted in the datasheet excerpt above. The specification is the time is takes for the device to go to 63% of T1 to T2.

    Best regards,

    Jesse

  • 0 in reply to Jesse Baker
    TI__Expert 3025 points

    Hi Jesse, 

    Thanks. And can you help point out which parameters shown in the TI temperature sensor datasheet can show the response time? 

    B.R.

    Lucas

  • 0 in reply to Zhizhao Niu
    TI__Expert 7795 points

    Hi Lucas,

    The parameters you should be looking for for thermal response are the ones you showed in your image above, tRES, or thermal response in the Specifications section. Additionally, some datasheets will include figures that show the thermal response, such as the image i've included below from the TMP23x datasheet.

    We don't have thermal response data for all of our sensors (you won't find it in every datasheet), but we would expect sensors with the same package to have similar response times. Additionally, the PCB mass is also a limiting factor in this kind of testing.

    Best regards,

    Jesse

  • 0 in reply to Jesse Baker
    TI__Expert 3025 points

    Hi Jesse, 

    Thanks. ANd I want to double confirm that what is this spec of TMP1075? I didn't find it in datasheet. 

    For TMP461, Is this below figure is the correct one? 

    For TMP126, Is this below figure is the correct one? 

    For LMT86, Is this below figure is correct one? 

    I also find that for different devices, the test condition is not same. May I know how could I compare the response time between them? 

    Thanks. 

    B.R.

    Lucas

  • 0 in reply to Zhizhao Niu
    TI__Expert 7795 points

    Hi Lucas,

    You are correct about the figures and specifications you found for thermal response of the TMP461, TMP126, and LMT86LPG.

    We don't have thermal response data available for the TMP1075, but as mentioned previously, sensors in the same package will have similar response time. For example, below is an excerpt from the TMPx75 datasheet, which are devices available in the DGK (VSSOP) and D (SOIC) packages like the TMP1075.

    If you are looking to compare response time across products, you would need to look for as similar test conditions as possible (PCB size, number of layers, and environment, such as stirred liquid or still air). Again, PCB mass will be a limiting factor in the thermal response of any sensor.

    Best regards,

    Jesse