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TLV9062: The offset voltage leap vs. common mode voltage.

Part Number: TLV9062
Other Parts Discussed in Thread: TINA-TI

Dear all

I find the Vos vs. Vcom curve as below:

We use TLV9062 as constant current source, which is very sensitive to the offset voltage leap. In order to simulate the offset leap, I use a voltage source doing parameter simulation. According to the results, if there is around 1mV leap on Vos, the output voltage will change around 58mV. But when we test on board, find there is no such leap at the output. So I want to know whether the TLV9062 has offset trimming circuit internally or not.

Tks and Regards.

  • Morning Feng, 

    Looks like you are doing simulations here, the crossover step in offset voltage is not modelled but would be there physically, here is the internal ckt simplified, 

    If you need to avoid that step, use a zero crossover device that uses an internal charge pump to keep a simpler input stage as per this discussion, 

    https://e2e.ti.com/blogs_/archives/b/thesignal/archive/2013/04/16/rail-to-rail-inputs-what-you-should-know

  • Hi Michael

    Thanks for your replying. Theoratically, this offset leap can be tested on our bench test. We use the same circuit as I simulated, but there is no large step on the output voltage. So I want to know the reason of this. Did TLV9062 have internal offset trimming in ATE process which narrows down the offset leap voltage?

    Thanks.

  • That is possible that it is trimmed, it is also possible you happen to have a very good unit that you are testing - if the design is a crossover type input, should expect some shift (not a leap) at crossover that will vary from part to part,

    The product group might have a zero crossover dual similar to the TLV9062

  • Former Member
    0 Former Member in reply to feng luo

    Hi Feng,

    Out of curiosity, I tried this simple test in TINA-TI to see if I could see this effect modeled.  It looks like they have tried to capture a worst-case scenario here.  But of course, different units will have different results and most units will not see an effect this severe in the real world.

    It's possible that you got a good part, as Michael has suggested.  I do not think there is some unannounced trim or performance improvement on this part.

    Can you explain how you ran your simulation?  Perhaps, more can be commented on that.

    If you are really worried about this, I would suggest picking a part with zero-crossover distortion, again as Michael has suggested.

    Regards,

    Daniel

  • Hey Daniel, I am impressed they tried to model this. 

  • Former Member
    0 Former Member in reply to Michael Steffes

    Hi Michael,

    Yes, I believe that there have been incremental improvements/additions to the GWL op amp model, which is now so popular here at TI, over the last few years.  I have seen the offset voltage modeling be more or less sophisticated, depending on the model.

    Take this with a grain of salt as I don't have experience working "on the inside" of too many of these models.  So, I think verifying the macro model with a simple test is the best way to go, at least for me.

    Regards,

    Daniel