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TIDM-HV-1PH-DCAC: ADC Sense Filter

Robin Houston
Intellectual 540 points
Part Number: TIDM-HV-1PH-DCAC

Hi There,

I'm reviewing the CCA and note that there is an RC filter on each of the ADC output pins, plus there are configuration elements entered into the main.cfg file for the Rfltr and Cfltr.

Two questions:

1. Please advise the rationale behind having RC filters between the OPAMP and the ADC input; Previous generation TI Eval boards (SOLAR-HV-DC-AC) didn't have this. Seems like a great idea (having the filter) just want to understand it.

2. Where is the Rfltr and Cfltr values used in the code? I did hunt through the code and could only see references in main.cfg and kit.xml.

Thankyou

Robin

  • 0
    TI__Guru 71585 points

    Robin,

    This post has been assigned to a TI employee familiar with the HV-1PH-DCAC kit.  Due to the July 4th holiday, we will get back to you no later than July 8th end of day.  Appreciate your understanding for the delay in response.

    Best,

    Matthew

  • 0
    TI__Mastermind 43730 points

    Robin,

    The filter can be used to eliminate high frequency noise from causing additional issues with the control loop. 

    Typically as switching noise is high, for slow moving signal the filter cutt off is kept lower than the switching frequency. For currents etc, it depends on the layout, sensor etc. 

    The values are not used by the software, they are mainly only used by the control loop tuning tool. 

    -Manish