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TMP421: Remote tmperature error

Jeff YANG
Mastermind 7835 points
Part Number: TMP421
Other Parts Discussed in Thread: DXP,

Hi,

The TMP421A reads temperature from the remote sensor, and the obtained values are all negative. We have tried swapping resistor and capacitor positions and values as per the datasheet, but it didn't work. However, reading the local temperature yields normal results.

Do we need to read or write any specific registers before reading the temperature from the remote sensor? Currently, we are setting the point register to 1 before reading the temperature value.

Thanks!

Jeff

  • 0
    TI__Genius 9730 points

    Hello Jeff,

    Glad to hear that your local temperature is working. Yes you are correct, communicating to the remote junction requires setting the point register to 1 before reading the temperature value. No additional commands are needed to read the remote junction. Did you try switching the connections between DXP and DXN? The TMP421 can sense a fault at the DXP input resulting from incorrect diode connection. Short-circuit conditions return a value of –64°C. 

    Best Regards,

    Meredith McKean