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TL431-Q1: Query on TL431 Response time as comparator

Sandeep Varma
Prodigy 140 points
Part Number: TL431-Q1
Other Parts Discussed in Thread: TL431

Hi, I have been simulating the TL431 as comparator. I have given green color waveform as input to ref pin. I could see the TL431 responding(blue color waveform) after > 100uS when ref pin voltage goes < 2.5V. Will TL431 takes this long to respond as i couldn't find the same in data sheet? 

  • 0
    TI__Genius 11391 points

    Hi 

    The spice model is result is not correct for comparator mode. 

    Typical silicon result has been poblished in app note SNVAA58  (Designing Stable Isolated Power Supplies with Shunt References).  Please refer section 4.2 (page 10) form comparator mode response time. 

    Regards

    Trailokya 

  • 0 in reply to Trailokya Rai
    Prodigy 140 points

    Hi, Do you mean spice file model is not correct? If Yes, Pls share the updated spice file for simulation.

  • +1 in reply to Sandeep Varma
    TI__Genius 11391 points

     Sandeep.

    We will update it in our next planned rev. I dont have correct file as of now. 

    Please let me know if you want any help is budget calculation. 

    Regards

    Trailokya 

  • 0 in reply to Trailokya Rai
    Prodigy 140 points

    Hi,
    I have query on TL431A. What is the forward voltage drop of the diode as marked below? we need this for some circuit analysis.

  • +1 in reply to Sandeep Varma
    TI__Genius 11391 points

    Sandeep 

    That is protection diode , that can withstand with 100mA current for a very short duration . However it is not recommended to design your circuit which regularly triggers this diode. It may lead to spec degradation. The voltage will be roughly around 0.6V but it can vary a lot with temperature , current and device to device as we don't design it to give stable output. That's why there is no spec given in the data sheet for the voltage. 

    You can refer

    Regards

    Trailokya