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TMP108: The TMP108 Design guideline

YU CHENG KUO
Prodigy 20 points
Part Number: TMP108

Hi TI team,

This is Archie from LUXSHARE-TW, we got a project that used TI temperature solution TMP108, and there are no enough information for me in the datasheet that I have so far, so I got following question need your support to clear that.

1. As far as I know, the temperature sensor need a vent in the case of device to detect the environment temperature, but there is no vent definition in the datasheet for the case of device.

We wonder whether the TMP108 need a vent in the case of device, and how much big is the vent that TMP108 need?

2. Does it need to prohibited routing area and cutting layers grounding under prohibited area?

3. What is the design notes about placement?

Thanks.

Archie

  • 0
    TI__Guru* 90906 points

    Dear Archie - 

    Welcome to E2E and thanks for posting!

    The recommendation depends on what you are trying to measure. (ambient temperature vs. PCB or component temperature)

    Please see this application note, from the TMP108 product page, which reviews the various layouts and how to place the sensor based on those scenarios.

    https://www.ti.com/lit/an/snoa967a/snoa967a.pdf

     

  • 0 in reply to Josh Wyatt
    Prodigy 20 points

    Hi Josh,

    Thank you for your support.

    If we expect to measure the ambient temperature, we need a vent on the case of device(ID), don't it?

    Thanks.

    Archie

  • 0 in reply to YU CHENG KUO
    TI__Guru* 90906 points

    Archie - 

    It really depends on your ultimate design goals and restrictions - you may do better if measuring ambient from inside a case by following the guidance found here: https://www.ti.com/lit/an/snoa966b/snoa966b.pdf  - perhaps peek at page 19, then work backwards in the document to see what will work for your design.

    I have also seen on some commercial remote temperature sensors for HVAC, where they install a copper (or other metal) disk in the housing itself, which then is arranged to conduct ambient heat into the housing, to the temperature sensor, which I think may speed up the response time in general, as air is a poor thermal conductor compared to metal.