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TMP451: Adjust Temperature Offset

Wei Liu89
Prodigy 130 points
Part Number: TMP451

Hi support,

We purchased one TMP451EVM for testing.

We used the TMP451EVM to test ASIC with integrated diode connected PNP transistor and compare against the other integrated diode connected PNP transistor physically located differently inside the ASIC.

We captured the TMP451EVM shows ~10 Celsius higher than from reading the other PNP transistor.

This seems an offset that need to adjust from TMP451EVM.

How can we write the registers to adjust the offset to lower 10 degree from the GUI? 

We see register offset 11 and 12 shows"Remote temperature offset".

Thanks,

-Wei

  • 0
    TI__Mastermind 43785 points
    Hi Wei,

    You should be able to type -10 into the 'Set External Offset' field and click GO. Are you seeing an issue with this feature?

    Thanks,
    Ren
  • 0 in reply to Ren Schackmann
    Prodigy 130 points
    Hi Ren,
    Thank you. Got it.
    Does that make sense if the reading is 10 Celsius degree between the 2 readings? I am trying to understand how this 10 degree difference come from? Which factor cause the difference?
    Thanks,
    -Wei
  • 0 in reply to Wei Liu89
    TI__Mastermind 43785 points
    Hi Wei,

    Can you clarify the nodes being measured? You mention two transistors; are you using two TMP451? Does your ASIC expose two transistors for temperature sensing? Can you take measurements with the ASIC powered off, and update your results?

    Thanks,
    Ren
  • 0 in reply to Ren Schackmann
    Prodigy 130 points

    Hi Ren,

    Thank you very much for your reply.

    1. We have two transistors. One is exposed for TMP451 to measure. The other one is not exposed but through reading through ASIC registers.

    2. When the ASIC is power off, there is no power to the system. So we expect the TMP451 read the transistor to be close to room temperature 23 Celsius degree. But the TMP451 reads the temperature to be about 33 Celsius degree and it is about 10 Celsius degree higher. What can be the root cause and how can we do to resolve this difference?

    Thanks,

    -Wei

  • 0 in reply to Wei Liu89
    TI__Mastermind 43785 points
    Hi Wei,

    It is likely that N-Factor setting in TMP451 needs to be adjusted for your ASIC. N-Factor correction is register 0x23. You will need to verify the temperature of your ASIC by another calibrated reference and use that to adjust TMP451 N-Factor. Once you select N-Factor Correction for your ASIC, it will work for all devices in production.

    Thanks,
    Ren