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Compiler/LMV792: How to use LMV792 Enable pin

Part Number: LMV792

Tool/software: TI C/C++ Compiler

Hello everyone, 

I have the next problem, I tried to simulate LMV792 like a trans-impedance amplifier to use with a photodiode.
I used the model of LMV792 in Multisim and TI.
But some strange things with Enable pins, because in the documentation to enable the channel need to connect V+ to Ven (i use the 5V).
But when I connect Enable pin I always have a voltage range 40mV, with different current from supply and different resistance.


What I do wrong?
Thank you for your help.

Kind regards,
Oleksii

  • Former Member
    0 Former Member

    Hello Oleksii,

    Thanks for your question and welcome to the forum.

    Would you please try to re-attach your images to the post?  I cannot see them currently.  We do not support Multisim, as it is a National Instruments product.  However, I might be able to tell what is wrong from looking at the schematic images once you re-post the images.

    Regards,

    Daniel

  • Hi.



    But how i wrote before, the same situation with your's software.
    In docs the minimum sensitivity of current 100fA.
    But with 50 nA i have the problems.

    Thank you, for your attention.
    Have a nice day.

    Kind regards,
    Oleksii

  • Former Member
    0 Former Member in reply to Oleksii Marchenko

    Hi Oleksii,

    What is the difference between the circuits you used for simulation 18 and 19?  You have different results, but the same schematic.  I'm guessing you made some change(s) to the current source.

    Could you send me your TINA file?  I think that would be the easiest way to fix this.

    Also just to be clear, what is the exact problem here?  Is it that you cannot sense the 50nA current even though you are expecting to be able to measure smaller currents?  When you say "docs," are you referring to the datasheet?

    Looking forward to your response and helping you solve this issue.

    Regards,

    Daniel

  • Former Member
    0 Former Member in reply to Oleksii Marchenko

    Hello Oleksii,

    I have not heard back from you in a little while.  Please let me know whether you need more help or I will have to consider your issue to be resolved.

    Regards,

    Daniel

  • Hi Oleksii,

    I guess you need a negative supply voltage when applying an AC current to the input of TIA:

    oleksii_lmv792.TSC

    Kai