• State Resolved
  • Locked Locked
  • Replies 7 replies
  • Answers 2 answers
  • Subscribers 49 subscribers
  • Views 1371 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TLV7031: Comparator Internal hysteresis

HARI T O1
Expert 1645 points
Part Number: TLV7031

Dear Team,

I am using TLV7031 in one of my designs. I can see that it has an internal Hysteresis of 7mV.

Please find my design calculation of feedback resistors. May I know where to accommodate this internal hysteresis in the equation.

I have few more  questions.

Let a comparator having an internal Hysteresis "X" mv.

  1. Does that mean the minimum achievable hysteresis is "X" mv"?
  2.  
  3. Is it possible to obtain a Hysteresis (Let it be "Y" mv) which is less than internal Hysteresis "X" mv using external feedback resistor network?
  4.  
  5. Will the external hysteresis set by the user will overwrite the internal Hysteresis or Does the internal and external Hysteresis will get added?

6)Could you please tell me the significance of internal Hysteresis? 

7)Will this internal hysteresis added to the designed hysteresis.

Regards

HARI

  • 0
    Guru 317060 points

    The internal hysteresis is not implemented with resistors. It is independent from any external hysteresis; the two simply add up.

    To reduce the internal hysteresis, you would have to add negative feedback.

  • 0 in reply to Clemens Ladisch
    TI__Mastermind 25990 points

    All good comments from Clemens.  Thank you.

    Only thing to add would be if less hysteresis is required, I would suggest a comparator that has minimal or no integrated hysteresis.

    Most low power applications are monitoring slow moving inputs, so having hysteresis is generally preferred to avoid the output from chattering as the input passes through the switching threshold.

    Chuck

  • 0 in reply to Chuck Sins
    Expert 1645 points

    Hi Chuck,

    Thank you very much.

    Internal Hysteresis will help when we used these comparators without any feedback.

    Regards

    HARI

  • 0 in reply to Clemens Ladisch
    Expert 1645 points

    Hi Clemens,

    Thank you very much.

    So the total hysteresis will be (Vih-Vil) + Internal Hysteresis.Please correct me If am wrong.

    "To reduce the internal hysteresis, you would have to add negative feedback." Could you please explain this.

    If we provide negative fb how the comparator operation will take place.

    Regards

    HARI

  • 0 in reply to HARI T O1
    Guru 317060 points

    Negative feedback would look like an op-amp circuit, i.e., the output influences VREF. (This is not something that I'd recommend you do, when comparators without built-in hysteresis are available.)

  • 0
    Guru 140200 points

    Hi Hari,

    a hysteresis of 7mV is very little. In my designs I always use a hysteresis to prevent ringing and oscillation and I always use a hysteresis which is way higher than 7mV to make the togglings insenstive to signal noise, EMI and supply voltage noise. Reducing the hysteresis to values below 7mV, on the other hand, is bad design practise and makes no sense to me. There's absolutely no advantage in using a comparator with no or only very little hysteresis.

    Kai

     

  • 0 in reply to kai klaas69
    TI__Mastermind 25990 points

    Hari

    Kai's comments are fair in general but there are some circumstances when comparators will little to no hysteresis are preferred.  Your application does not appear to be one of those, so you can proceed as you planned.

    It appears that your question has been answered, so I will be closing this post.

    Thanks everyone for your continued support and the excellent responses from Clemens and Kai.

    Chuck