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TMS320F28379D: ADC performance of LAUNCHXL-F28379D

Naoki.N
Intellectual 515 points
Part Number: TMS320F28379D
Other Parts Discussed in Thread: LAUNCHXL-F28379D, TMDSCNCD28379D

Hi

I want to evaluate the performance of TMS320F28379D,　I experimented under the following conditions using Launch-Pad(LAUNCHXL-F28379D).

<condition> 

-I evaluated in 16-bit differential input mode using ADCINA0 and ADCINA1.

-To evaluate voltage supply noise influence, ADCINA0 (J3 10pin) and ADCINA1(J7 10pin) connect GND.

<result>

I measured 200 times of ADCRESULT1 the result is following graph.

There was a variation of 21 dec.

Is it necessary to increase the accuracy of VDDA to further improve the accuracy of ADCRESULT?

Or is it necessary to improve Ref voltage accuracy?  I think REF5030 in Launch-Pad is sufficient spec, is that correct?

Best regards

Naoki

  • 0
    TI__Guru 62975 points
    Naoki.N said:
    I experimented under the following conditions using Launch-Pad(LAUNCHXL-F28379D).

    Do keep in mind that the LaunchPad was designed to be a low-cost EVM, rather than a mid-performance EVM (like the TMDSCNCD28379D). The ADC A0 and A1 signals are connected directly to the LaunchPad headers with no on-board signal conditioning or buffering components that would be common for high precision ADC sampling. A differential buffer is provided for ADC D4 and D5 for improved evaluation.

    Naoki.N said:
    To evaluate voltage supply noise influence, ADCINA0 (J3 10pin) and ADCINA1(J7 10pin) connect GND.

    Tying both pins to GND will violate the datasheet requirements for maintaining a common-mode voltage of (VREFHI + VREFLO / 2):

    Naoki.N said:

    There was a variation of 21 dec.

    Is it necessary to increase the accuracy of VDDA to further improve the accuracy of ADCRESULT?

    The noise is most likely coming from the input path to the ADC channels. The differential buffer should provide better results, provided that the common-mode voltage is maintained within the datasheet requirements.

    Naoki.N said:
    Or is it necessary to improve Ref voltage accuracy?  I think REF5030 in Launch-Pad is sufficient spec, is that correct?

    Yes, the REF5030 is sufficient.