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TMS320F28062 and ADC rails

BobW
Intellectual 280 points

The datasheet for the TMS320F2806x indicates that "The ADC converts from 0 to 3.3-V fixed full scale range..." (p. 2, and similarly in ADC Characteristics on p. 86) while An Overview of Designing Analog Interface With TMS320F28xxx DSCs (SPRAAP6A) states " The voltage applied to the ADCIN pins should be restricted between 0 V–3 V... (p. 16).

I am a little unsure how to interpret the apparent difference here. Is it that  the TMS320F2806x is newer/upgraded and therefore better able to handle ADCIN voltages above 3.0V but below 3.3V? Will input voltages above 3.0V but below 3.3V negatively impact readings on any ADC channel of the TMS320F2806x?

Thanks in advance for time and help.

  • 0
    Guru 20525 points

    Hi Robert!

    You need to refer to datasheet of specific DSC series or specific DSC (at your case refer to TRM of TMS320F2806x  -  SPRUH18D (Ch.8.1.1 &  8.1.10)) 2548.TI_TMS320x2806x_TRM.pdf. Thus the ADC range is 0 - 3.3 V. 

    Regards,

    Igor

  • 0 in reply to Igor Gorbachev
    TI__Guru 60865 points

    Hi again Robert,

    To add a little bit to what Igor said, the F2833x and earlier C2000 devices have a fixed ADC conversion range of 0 to 3V.  Newer devices like the F28062 have two options: a fixed 0 to 3.3V range provided by the internal reference, or a ratiometric range with respect to VREFHI/VREFLO pins.    

    On the F2833x and earlier devices, it is particularly important to not exceed the full scale range (3.0V in this case) because the accuracy of conversion results on other channels can be affected.  On F28062 and other Piccolo Family devices, this is no longer an issue, but you will definitely still want to keep input voltages within the full scale range (0 to 3.3V or VREFLO to VREFHI).

    Also note that the ADC wrapper for Piccolo series devices is different than F2833x and earlier devices (Piccolo uses an SOC based triggering scheme, while earlier devices use a sequencer), so some of the information on software setup from the referenced app note will not be applicable. 

                  

  • 0 in reply to Devin Cottier
    Intellectual 950 points
    Hi Robert,

    I had the same question and recently empirically determined it was 0-3.3V.