• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 82 subscribers
  • Views 339 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TMS320F28388D: Relationship between ADC Zero Offset Calibration and OTP calibration values

K.Z
Genius 3215 points

Part Number: TMS320F28388D

Tool/software:

Hi All,

Re-calibrate the ADC offset in 12-bit single-ended mode using the TRM [20.11.1 ADC Zero Offset Calibration] method.

The OTP area stores the ADC calibration value, which can then be read back. [20.11 ADC Calibration]

Can the OTP value be ignored when using the TRM (20.11.1 ADC Zero Offset Calibration) method?

Best Regards,

Ito

  • +1
    TI__Genius 11081 points

    Hello Ito,

    If you recalibrate offset as described in the TRM, the measured calibration value replaces the OTP value. You will need to make sure you write your calibrated offset trim value to the register after calling SetVREF/initializing the ADC to make sure the ADC is using the newly calibrated offset trim value and not the OTP value.

    Best regards,
    Ibukun

  • 0 in reply to Ibukun Olumuyiwa
    Genius 3215 points

    Hi Olumuyiwa,

    Thank you for your reply.

    Last question.
    The TRM mentions that the DAC offset calibrated with a 2.5V reference voltage.[21.2.2 DAC Offset Adjustment]
    So what is the reference voltage when calibrating the ADC?
    We use Vref=3.3V, so the DAC is corrected from 2.5V to 3.3V.
    Is it necessary to correct the ADC as well?

    Best Regards,

    Ito

  • 0 in reply to K.Z
    TI__Genius 11081 points

    Hello Ito,

    No, this is not needed for the ADC.

    It is required for the DAC because the DAC is generating an analog voltage, but the offset trim value is a digital code. So, the resulting output voltage will vary depending on what the reference voltage is. For the ADC, the output is a digital code, so the reference only affects the input signal. The offset trim is applied after the signal has been converted to a digital code.

    Best regards,
    Ibukun