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LMV341: Regarding input voltage

Kenji Ohno1
Genius 5095 points
Part Number: LMV341

Hi Team,

Customer changed from LMV 342 to LMV 341.

The input terminal (+) potential was 200 mV and the input terminal (-) was 150 mV.

In the case of LMV 342, the input terminal (-) was also 200 mV.

I would like to know the cause.

LMV341.pdf

Best Regards,

Kenji

  • 0
    TI__Mastermind 30600 points
    Hi Kenji-san,

    When the circuit uses LMV341, does it work?

    It looks like your schematic might have the inputs switched. Can you confirm that positive feedback is actually used?

    Maybe what you are seeing is a device to device difference in input bias current and that is impacting the offset voltage.

    Any further information like measured data and input conditions would be helpful.

    Thank you,
    Paul
  • 0
    Guru 140200 points
    Hi Kenji,

    I agree with Paul, the circuit looks rather strange...

    Is the 0.47pF cap in parallel to the 7k5 resistor or in series to the photodiode?

    Is it a photodiode or a LED?

    And, as Paul already asked, are the inputs of OPAmp swapped?

    Shall the circuit be a TIA with bias?

    Kai
  • 0 in reply to kai klaas69
    Genius 5095 points

    Hi Paul-san, Kai-san,

    I'm sorry.

    I corrected it because there was a mistake in the circuit diagram.

    The diode is a photodiode.

    LMV341_2.pdf

    Best Regards,

    Kenji

  • 0 in reply to Kenji Ohno1
    TI__Mastermind 30600 points
    Hi Kenji-san,

    Can you provide the answer to these questions:

    * When the circuit uses LMV341, does it work?
    * How much current does the photo-diode provide?
    * Did the type of photo-diode change between the circuits?
    * Do you have any additional information (measured data, input conditions)?

    Thank you,
    Paul