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TMP513 Remote Sensor Question

Daniel Morgan
Prodigy 20 points
Other Parts Discussed in Thread: TMP431

I was reading the data sheet and saw that it says that i can use NPN-, PNP-, or a diode to sense temps remotely. Anytime I see something this broad it worries me a bit. I am wondering if this really will work with any of these devices? Do some transistors or diodes work better than others? Do they give different temp ranges?

  • 0
    TI__Mastermind 27715 points

    Hello Daniel,

    Yes, NPN, PNP, or diodes will work as a remote sensor over the full temperature range of the TMP431. However, there are specific parameters that are important when selecting a remote device. They are:

     

    1. VBE > 0.25V at 6µA (minimum excitation current)
    2. VBE < 0.95V at 120µA (maximum excitation current)
    3. Base resistance < 100Ω 
    4. Small variations in hFE (50 to 150) 

     

    The simplest approach is to use one of our recommended transistors, either the 2N3904 (NPN) or the 2N3906 (PNP). I'd recommend the 2N3906 since it was used in our characterization system. 

    Best regards,

    Ian Williams
    Linear Applications Engineer
    High Performance Linear and Sensing Products