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ADS8028: Internal Temp Sensor Sampled Values deviate depending if there RF pulses in the board compare to when no RF pulses exist

arye nudelman
Intellectual 255 points
Part Number: ADS8028

Tool/software:

Hi,

we use in our board and see such strange problem.

we though maybe the specfic assembled IC had issue but replacing the specific IC with new one, didn't solve the issue, it a bit change the behavior, but the issue is there.

what could be the reason?

note only the internal temp sensor reacts to the present of RF pulses on the board. not other sampled voltages.

we use internal Vref = 2.5V, but as i mentioned above only the internal temp sensor influenced 

  • 0
    TI__Guru**** 180821 points

    Hi Arye,

    Can you provide a little more detail?How are you using the internal temperature sensor, normal or averaging mode?  What is the nature of these RF pulses?  How near to the RF source is the ADS8028 located?  What impact are you seeing?

  • 0 in reply to Tom Hendrick
    Intellectual 255 points

    hi thanks,

    i will answer in more details tomorrow, but what we do is:

    - sample the int. temp value in a loop, in fast rate, each 1 second or half second

    - we see stable temp value

    - once we start RF pulses that are in our board the temp changes few degraes, on the first chip we saw 10 deg C. change.

    - when you stop the RF pulses the temp value start go back to the value it was stable with at the begining before turning the pulses.

    other Ain are not have same behavier , only the temp value has such.

    right now im not sure if the sample are average or normal. 

    the rf pulses exists on the pcb traces, i'm not sure right now how exactly they close to the IC, but i think the IC has same GND etc.

    this topic in your forum seems to be very similar to our issue, its just that you contine to discuss via mails

     ADS8028: Temp sensor output value error at electromagnetic field immunity test 

    Thanks 

    Arye