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TMP101: Does TMP101 sense the temperature of the pin or of the ambience?

Wayne Wang20
Expert 4360 points
Part Number: TMP101

Hi team,

I want to check with you that does TMP101 sense the temperature of the pin or of the ambience?

In the datasheet, it claims as below

My understanding is that the GND pin is the primary path to conduct the temperature of the heat source to TMP101 inside. So does this mean TMP101 internal sensor is actually sensing the temperature on its GND pin? Can you help explain more detail about the temperature sensing location? Thanks.

Best regards,

Wayne

  • 0
    TI__Mastermind 35895 points

    Hi Wayne,

    In the case of TMP101, the DBV package has the metal for pin 2 (GND) extended beneath the sensor IC. The other pins do not have metal that extends this far into the package structure. This is why the datasheet has the note about GND being a good thermal path to the sensor. Unfortunately, we don't publish the internal drawings for the package/leadframe, so customers are not able to see this metal structure. 

    All of our local temperature sensors, including TMP101, are sensing the temperature of the silicon IC itself. With time, the IC will reach thermal equilibrium with its surroundings. The plastic packaging has a lower thermal conductivity and will transfer heat to the sensor less efficiently than the metal pins, but all heat sources contribute. If the goal is to measure ambient air temperature, then the layout should be adjusted to thermally isolate the sensor from PCB heat sources. We discuss this in the app note https://www.ti.com/lit/snoa967

    thanks,

    ren