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TSC2046: temperature sensor output has error

Guru 11170 points
Part Number: TSC2046

Hello E2E,

Could you attach your comment about following URL?

https://e2e.ti.com/support/other_analog/touch/f/750/t/693097

Regards,

ACGUY

  • Part Number: TSC2046

    Hi E2E members,

    According to Data Sheet, the accuracy of TEMP0 is ±3℃.

    And then, Data Sheet have folloing coment.

    "During the final test of the end product, the diode voltage
    would be stored at a known room temperature, in memory,
    for calibration purposes by the user, if we use data of TEMP0. "

    Do we not need to do the calibration, if we can acceptable to
    dfference of temp by ±3℃?

    Regards,
    Nao

  • Hi, E2E members

    Can anybody tell me? My customer are waiting for the reply.
    Does TSC2026 achieve ±3℃ accuracy without calibration?

    Regards,
    Nao
  • Hi, E2E members

    Someone please answer my question.

    Regards,
    Nao
  • Nao,

    I apologize for the long delay on this answer.

    1. Notice that the temperature accuracy is typical. Typical means that most devices will have an accuracy of this level. To be more specific the typical limit will be +/- 1 standard deviation, or 68% of the population. So, using the differential method 68% of the devices will be +/-2⁰C. Some devices will have a larger error than this. For example, +/-3 standard deviations (+/-6⁰C ) will contain 99.73% of the population. See the precision labs video series on error analysis to get a better understanding of this: Error Analysis on ADC Systems

    2. The reason the error limits are not more accurate is because of the diode non-ideality factor. The equation in the data sheet does not include the non-ideality factor. In reality the equation is multiplied by the factor n which typically ranges from 1 to 2. The full equation for a diode is covered in page 74 and 75 of the Analog Engineer's Pocket Reference. This factor is from process variation on the diode.

    3. Another approach: Temperature sensor devices are optimized for very high temperature accuracy. They will have absolute maximum limits for temperature whereas the touch screen controller only gives typical limits. These devices come in a varity of accuracy, cost, and package sizes. I know you would prefer to use the on board sensor on the touch screen controller but you could use a discrete temperature sensor for a high accuracy (with a max limit).  Check here for different temperature sensor option: Temperature Sensor Search

    4. Bottom line: if you really need high temperature accuracy you will need to calibrate the system, or use a discreet temperature sensor.

    I hope this helped. Again, sorry for the delay.