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The maximum error of MibADC on TMS570LS2125

Guru 16760 points
Other Parts Discussed in Thread: TMS570LS2125, HALCOGEN

Hello,

I have a question for "Table 5-10. MibADC Operating Characteristics Over Full Ranges of Recommended Operating Conditions" described in page 121 of data sheet of TMS570LS2125 (spns164).
Is ETOT (Total unadjusted error) equal to the maximum error?
I think that 10-bit mode maximum error is plus or minus 2% and 12-bit mode maximum error is plus or minus 4% (after calibration).
Also, in case of not after calibration, error becomes larger.

If not so, could you teach me the maximum error for both of 10-bit mode and 12-bit mode?

Best Regards.

Nomoto

  • Please find the answers embedded in your question

    I have a question for "Table 5-10. MibADC Operating Characteristics Over Full Ranges of Recommended Operating Conditions" described in page 121 of data sheet of TMS570LS2125 (spns164).
    Is ETOT (Total unadjusted error) equal to the maximum error?

    Answer >>> Yes, the total unadjusted error is the maximum error (combination of DNL, INL, gain and offset)


    I think that 10-bit mode maximum error is plus or minus 2% and 12-bit mode maximum error is plus or minus 4% (after calibration).

    Answer >>>  At 10bit mode error is +/-2LSB and 12 bit mode is +/-4LSB.


    Also, in case of not after calibration, error becomes larger.

    Answer >>> Yes, without calibration, offset and gain could cause the error to be larger.

    -Hercules forum support

  • Hello,

    Thank you for your reply.
    And I have one more question.
    I think that there are two types of calibration sequence, "19.8.1.2 Calibration and Offset Error Correction Sequences" and "19.8.1.3 Mid-Point Calibration", described in TRM (spnu499).
    When the calibration is operated, which sequence is processed?

    Best Regards

    Nomoto

     

  • Have you got any update for this question?

    Best Regards

    Nomoto

  • i will provide an update tomorrow.

     

    -Hercules forum support

  • Hello,

    The calibration sequence is not implemented completely in hardware and is a software-managed routine.

    HALCoGen generates the functions for both the 4-point calibration as well as the mid-point calibration sequences.

    The 4-point calibration sequence uses four reference voltages to compute the average offset error. The reference voltages include zero-scale, full-scale and the two mid-points.

    The mid-point calibration sequence computes the average offset error using just the two mid-point reference voltages.

    Regards, Sunil

  • One more correction / clarification:

    The ADC total error specified in the datasheet is actually the error you can expect without any calibration. This will be corrected in future datasheet updates.

    Regards, Sunil

  • Hello Sunil-san,

    Thank you for your reply.
    I understand the ADC total error in the datasheet is actually the error without any calibration.

    Now, could you teach me the ADC total error with calibration for the 4-point calibration sequence and the mid-point calibration sequence?

    Best Regards

    Nomoto

     

  • Hello,

    If the ADC’s internal offset and gain errors are a significant component of the total error, then you can expect the accuracy to be improved by using either the 4-point or the mid-point calibration sequence.

    Regards,

    Sunil

  • Hello,

    You said "The ADC total error specified in the datasheet is actually the error you can expect without any calibration."
    So, I want to know the ADC total error after calibration by using either the 4-point or the mid-point calibration sequence.
    Could you determine?

    Best Regards

    Nomoto