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TMS320F28374S: Voltage Reference to couple with 374S

Antonio Faggio
Expert 7930 points
Part Number: TMS320F28374S

Hi,

My customer needs to replace F28334 with TMS320F28374SZWTT.

Currently they acquire an analog signal via the internal ADC of the DSP using the internal Voltage Reference of 28334 and the accuracy of the measurement is ok for customer.
The new DSP 374 instead requires an external voltage reference.
I therefore need to understand the accuracy of the internal voltage reference of 28334 as it is not explicitly stated in the datasheet.


Customer needs this parameter to then choose the most appropriate (and not unnecessarily expensive) voltage reference for the 28374.
In the evaluation board of 28374 TI uses a very powerful voltage reference (REF5030IDGKT at $ 3.15), surely because the ADC of 28374 is much more accurate than that of 28334 but customer is interested in maintaining the current accuracy of 28334 therefore customer is looking for some suggestions to combine a less expensive voltage reference (example REF5030AIDGKT at $ 1.29 or a REF3030AIDBZR at $ 0.48).

Any comments here> You can also reach me in private for further discussions.

Many Thanks,

Antonio

  • 0
    TI__Guru 60865 points

    Hi Antonio,

    Ultimately the reference will affect the gain error specification.  What you want is to select an external reference such that the RMS sum of reference + gain error = F2833x internal reference gain error.  

    e.g. if the external reference is 0.5% accurate across the temperature range of interest:

    0.005 * 4096 = 20.5 LSBs

    and F28377x has a gain error specification of 5LSBs, then:

    sqrt(20.5^2 + 5^2) = 21.1 LSBs, which is less than F2833x gain error spec' of 30LSBs.