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ADC Configuration application notes for DC-DC converter output voltage sensing

narendar rao
Prodigy 10 points
Other Parts Discussed in Thread: TMS320F28027, CONTROLSUITE

Hi,

I am converting my existing analog controlled full bridge DC-DC converter to digital by using TMS320F28027 and i have few queries on ADC configuration. In this analog control, the switching frequency was 165kHz and the output voltage ripple frequency was 330kHz (double the switching frequency). Now as the load increases the ripple voltage will increase and the sensed output voltage (scaled down to below 3.3V) to the ADC will vary accordingly. 

1) How to configure the ADC channels for any DC-DC converter by considering the parameters like switching frequency & output ripple voltage.

2) How to configure the  software filters (low pass or moving average) to filter out the noise in the sensed signal?

3) Are there any application notes on ADC configuration (C2000 controllers) for DC-DC converters.

Please suggest me.  

  • 0
    Guru 192875 points

    Hi Narendra,

    narendar rao said:
    1) How to configure the ADC channels for any DC-DC converter by considering the parameters like switching frequency & output ripple voltage.

    So first step would be eliminate the major noise components to ADC by designing a proper RC filter. Secondly you can use a Moving Average in software.

    narendar rao said:
    2) How to configure the  software filters (low pass or moving average) to filter out the noise in the sensed signal?

    So in my case I'd designed a Notch filter and a Moving Average on my own but you can find some pre-implemented filters libraries in "libs" section of controlSuite.

    narendar rao said:
    3) Are there any application notes on ADC configuration (C2000 controllers) for DC-DC converters.

    You can find the ADC based controlSuite examples here:

    C:\ti\controlSUITE\device_support\f2802x\v230\f2802x_examples_structs


    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    TI__Guru 57255 points

    Good thoughts from Gautam. 

    I would also note that it is possible for the ADC sampling to be triggered from the PWM, which is controlling your power stage.  You can configure the sampling point such that the ADC samples away from the switching noise (and samples the average current, when current is being sensed).