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TLV9102: What is the maximum output swing for the opamp TLV9102 considering an input common mode at the opamp rails (0V to +Vcc)

Bruno Simard67
Prodigy 200 points
Part Number: TLV9102

Hello,

From my understanding of the Output voltage swing specification of the datasheet from rails, I should be able to reach value lower than 48mV on the negative rail. While the simulation run on TINA calculated 48mV for load varying from 2K to 10K.

So my question, is the TINA simulator is correct? 

Thank you

Regards

Bruno

See my TINA project attached

TLV9102_output_swing.TSC

  • Former Member
    0 Former Member

    Hello Bruno,

    Under the proper conditions, the answer would be yes.  Technically, your circuit is not set up in the same manner as the data sheet specifies.  However, I think it should still work.

    Please allow me to look into this more and I will get back to you with at least an update tomorrow.

    By the way, your image did not attach properly.  I've found that I have issues when I simply copy and paste the image into the text box.  Instead, try pressing the "Insert/Edit Media" button.

    Regards,
    Daniel

  • Former Member
    0 Former Member

    Hello Bruno,

    Thank you for your patience.  I am having the engineer responsible for simulations take a look at this.  For the time being, please assume the data sheet is correct while we try to sort out the situation with the model.

    I will have my next update for you by Monday (US time).  Please let me know if you have any further questions in the meantime.

    Regards,
    Daniel

  • 0 in reply to Former Member
    Prodigy 200 points

    Hello Daniel,

    Thank you for the feedback. This is all the time appreciated

    Regards

    Bruno

  • Former Member
    0 Former Member in reply to Bruno Simard67

    Hello Bruno,

    It turns out that the models simulate the output voltage and current based off the claw curve figures of the data sheet.  Now the claw curves are valid for a particular supply voltage and load impedance.  So deviating from those conditions you will no longer get an accurate simulated output at the rail limit in terms of exact output voltage.

    For example, if you were to have an amplifier in a single-supply configuration (for example Vcc = 5V and Vee = GND) and the load were tied to GND, then the output low voltage would be very close to GND.  But, I would not expect our models to simulate this unfortunately.  For this type of behavior, it would probably be best to try something out in real life...or trust the data sheet.

    Hopefully this answers your question and is not a significant hindrance.  Please let me know if you have any other questions about the models.

    Regards,
    Daniel

  • 0 in reply to Former Member
    TI__Mastermind 18557 points

    Hey Bruno, 

    To add to Daniel's statements, you may find the complete list of simulated parameters in the TINA reference design: 

    As Daniel mentioned, Vo is modeled after the Output Voltage Swing vs. Output Current (which is Figure 14 and 15 of the datasheet). The conditions for that graph are at Vs=16V and RL=10k. The experiment of your TINA file (changing RLs for Vs=2.7V) are not modeled and would not show the expected output. 

    All the best,
    Carolina

  • Former Member
    0 Former Member in reply to Bruno Simard67

    Hi Bruno,

    Since I have not seen your feedback yet for these responses, please let me know if you have anything to add or ask.  Otherwise, I will have to assume that the issue has been resolved.

    Regards,
    Daniel

  • 0 in reply to Former Member
    Prodigy 200 points

    Hello Daniel,

    I don't want to spend to much time on this but I'm still convinced that there is something wrong into the spice model. Since I redo the simulations many time with many loads (above 10K) and many different Vcc, I observed all the time the same behavior. The first bug appeared because of the spike and  followed the abnormal offset problem ...

    Finally, you can close this ticket. I will try to test the part physically on the board and/or I will change of part because I really need to get a very low offset reaching the negative rail

    Thank you for your time

    Regards

    Bruno

  • Former Member
    0 Former Member in reply to Bruno Simard67

    Hello Bruno,

    You are correct in that the spice model does not model the output behavior for all output loads.  I am not in disagreement with you here.

    If you have a single supply and a load tied to ground, the output of the amplifier will reach very close to ground and much more than the spice model would suggest.  This is nicely explained in this blog post by Bruce Trump.

    Regards,
    Daniel