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TMS320F28069: the impact of Comparator Block on ADC

Seven Han
Intellectual 600 points

Part Number: TMS320F28069

hello,as the title says，if comparator block doesn't initialize，does it affect the use of ADC?

When doing a test, it is found that if the ADC Comparator Block initialization program is removed, the test will be problematic，it is probably related to ADC sampling；In fact, ADC Comparator Block function is not needed.

Thank you.

  • 0
    TI__Genius 17370 points
    Hello,
    I am writing to let you know that a C2000 team member has been assigned to this post and should be answering shortly.

    Regards
    Baskaran
  • 0
    TI__Mastermind 28275 points

    Hi Seven,

    The comparator and ADC share some components: pin and bandgap. However, enabling or disabling the comparator shouldn't have any effect on the ADC performance because the comparator input is fairly high impedance and the bandgap was designed to work well with both.

    Can you elaborate more on the problem you are seeing when you remove the initialization code for the comparator? Is the ADC giving bad performance or is it not working at all? Also if possible, can you post the comparator block initialization code?

  • 0 in reply to Frank Ankapong
    Intellectual 600 points
    Thank you for your confirmation,Frank.
  • 0 in reply to Seven Han
    TI__Mastermind 28275 points

    Hi Seven,

    Depending on your source strength, the ADC can experience some performance degradation due to the small current draw from the 100K hysteresis feedback resistor connecting the output of the comparator to the positive input. The comparator hysteresis is enabled by default but can be disabled using the "COMP HYSTERESIS CONTROL" register found in the ADC registers. This is most likely what you are seeing. We'll make a note of this in the documentation.