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CCS/TMS320F28069: F28069 ADC grounding and differential mode measurement

Liyao Wu
Prodigy 70 points
Part Number: TMS320F28069

Tool/software: Code Composer Studio

Hello,

I am using a F28069 microcontroller board to do an ADC of a DC-DC power converter. The microcontroller is using an analog ground and the voltage I want it to measure is referenced to the power ground. If I do it this way, there will be large noise present on the ADC node. I solved the problem by changing the ground of the microcontroller to be the power ground instead of the analog ground. However, I do not think this is a good idea and sometimes when I increase the voltage of the DC-DC converter, the CCS will give out warning and disconnect the microcontroller (it is connected via USB to a laptop.). 

Would you please help to give some advice on how to properly setup the microcontroller in this case and allow accurate measurement of a signal of a different ground? Is there differential mode measurement for the ADC of the F28069?

Thank you very much! 

  • 0
    Guru 192875 points

    Hi,

    Liyao Wu said:
    Would you please help to give some advice on how to properly setup the microcontroller in this case and allow accurate measurement of a signal of a different ground?

    Let me share what I follow, I've 2 GNDs in my controlCard AGND (Analog Ground) and DGND (Digital Ground). These 2 Grounds get connected together through a 0R resistor or a Ferrite bead. Again, AGND is connected to PGND (Power Ground) at the lowest noise point for eg. DC Bus Capacitor Negative.

    Liyao Wu said:
    Is there differential mode measurement for the ADC of the F28069?

    No, F28069 doesn't have a differential mode ADC.

    Regards,

    Gautam