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LM34 Negative Voltage

Alvin P. Schmitt
Intellectual 940 points
Other Parts Discussed in Thread: LM34, LMT87

On the LM34 datasheet page 14 Figure 17 it shows how to use two diodes to get to a negative temperature. I am confused as how to present this to a microcontroller's Vref- and Vref+ inputs for the AtoD. Would the negative output on the figure be connected to the Vref- of a microcontroller with AtoD?

  • 0
    TI__Expert 7220 points
    Hi Alvin,

    Let me look into this and get back to you.

    -Michael Wong
  • 0
    TI__Expert 7220 points
    Hi Alvin,

    Usually a microcontroller's Vref- and Vref+ pins are used to measure the internal reference voltage and not used as inputs to the ADC. For Figure 17, if your microcontroller has differential inputs for the ADC, connect the + and - connections in the diagram to the + and - inputs of the ADC. There are newer parts with better implementations and accuracies for negative temperatures, one part to come in mind is the LMT87. What microcontroller are you interfacing with?

    -Michael Wong