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Semiconductor Temperature Sensing

Steven Brown4
Prodigy 10 points
Other Parts Discussed in Thread: TMP116

Hi, I'm looking for advice and someone with allot more knowledge than I have in regards to Digital IC Temperature senor chips.

Basically my understanding of a surface mount IC chip is:

  1. That it records the track of a PCB or ambient temperature of the surrounding air,...I might be wrong but could do with clarification on this?
  2. This is more a Application Question, Could the digital chip, instead be fitted onto a flexible PCB (thin film) and be used to record a temperature of a surface accurately (So that chip would directly be in contact with a surface (brass bar for example)?

its a bit out there, so excuse my poor knowledge.

  • 0
    TI__Mastermind 43785 points
    Hi Steve,

    The temperature 'transducer' is the silicon/semiconductor itself. Our measurements are based on the physical properties of a transistor; see en.wikipedia.org/.../Silicon_bandgap_temperature_sensor.

    If you disassemble one of our products, you would find the semiconductor device encapsulated by plastic with the metal contacts electrically connected by fine gold wires. You can see lots of pictures of this if you do a google search for "integrated circuit decapsulation."

    Keeping in mind that the silicon is the transducer, you have to consider what is the dominant thermal path to this transducer. In many cases, the only contact that can be made is with the plastic. We know that plastic has a relatively poor thermal conductivity. Depending on the packaging, there may be exposed metal that the silicon rests on. TMP116 features an exposed thermal pad like this. Typically, these thermal pads are used to extract heat from a high power device. In our case, the thermal pad offers a path to the temperature transducer with very good thermal conductivity.

    Please see the app note "Temperature Sensors: PCB Guidelines for Surface Mount Devices" for more information on this topic. www.ti.com/.../snoa967.pdf

    Thanks,
    Ren