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ADS1248: The ADC sampling value begins to increase abnormally when the ambient temperature exceeds 100℃

Hui Cao22
Intellectual 670 points
Part Number: ADS1248
Other Parts Discussed in Thread: ADS124S08

Tool/software:

At present, we use ADS1248 for pressure sampling, and the ADC sampling value begins to increase abnormally. When the ambient temperature exceeds 100 ℃, the applied ambient temperature is 120 ℃, and the ADC internal reference is adopted. What might be the cause?

  • 0
    TI__Mastermind 43021 points

    Hi Hui Cao22,

    The ADS1248 is only specified to 105C, so it is possible you are getting issues because you are nearing (or exceeding) this rating. What exactly are the issues? Can you describe them in more detail, provide plots, etc.?

    And how can you be sure it is not the pressure sensor, or other components on the board that are causing the issue?  

    Hui Cao22 said:
    When the ambient temperature exceeds 100 ℃, the applied ambient temperature is 120 ℃, and the ADC internal reference is adopted.

    I don't understand this sentence. how can the ambient temperature be 100C and 120C?

    -Bryan

  • 0 in reply to Bryan Lizon86
    Intellectual 670 points

    many thanks for reply, what is difficult from Operating ambient temperature and specified ambient temperature, our pressure sensor can support 200℃.

    and if the ADS1248 can't support 120℃， could you recommend part，thanks.

  • 0 in reply to Hui Cao22
    Intellectual 670 points

    Another our product is also working at 120℃, and ADS1248 works normally. Is it the PCB layout problem? Is there any requirement for the layout of this chip?

  • 0 in reply to Hui Cao22
    TI__Mastermind 43021 points

    Hi Hui Cao22,

    The ADS1248 operates up to 125C, but the electrical characteristics are only characterized up to 105C. So the part should function up to 125C, but you can expect changes in the performance when the ADC die temperature is >105C

    Can you provide more information about what is going on? It is always possible that  I asked for more information in my last post and you did not provide it.

    You can also consider the ADS124S08, which is the next-generation of the ADS1248. The ADS124S08 is specified over the temp range shown below. However, if you determine that the issue is not because of the ADC, changing to a different ADC will not help you. So it probably makes sense to look into what the issue is and make sure it has something to do with the ADS1248 behavior when ambient temperature is >105C

    -Bryan