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Connecting multiple thermistors in parallel

Revenant
Prodigy 80 points

Other Parts Discussed in Thread: TMP104, TMP107

Hello,

I am planning to connect nine 100KOhm thermistors in parallel to measure temperature across 9 cells. The 25 degC resistance is 100K.

However when in parallel the effective resistance is 11.1K which when mapped into the thermistor look-up table maps into approx. 78 degC.

Is there a better way to connect thermistors in parallel and obtain the right temperature in h/w or s/w ?

Regards

  • 0
    TI__Genius 12780 points
    Hi Revenant,

    Do you want the effective resistance to be 100 kOhm? Do you need all 9 cells to be in parallel? A series-parallel approach might let you better balance the circuit in order to achieve 100 kOhm effective resistance. For example, have three parallel branches, each branch having three 100kOhm thermistors. 1/(1/300k + 1/300k + 1/300k) = 100k.

    Hope that helps.

    Dan
  • 0
    TI__Mastermind 46455 points
    Hi Revenant,

    I'll let Daniel answer your thermistor question, but you might consider using a daisy-chain product like TMP107 or TMP104 instead. These products use robust UART communication to provide accurate temperature measurements at several nodes using a minimal number of wires.

    Thanks,
    Ren