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LMV342 / Oscillation by TINA-TI

Kuramochi Tadahiko
Guru 28715 points
Other Parts Discussed in Thread: LMV342, TINA-TI, LMV824-N

Hi,

Oscillation is doubted on the my customer's circuit used the LMV342.

So we would like to confirm operation with the my customer's circuit by TINA-TI.

Can we look oscillation of the LMV342 by TINA-TI?

I think that oscillation can't be observe because II tried to simulate with the attached file, however I can't observe oscillation.

LMV824 Oscillation.xlsx

Best Regards,

Kuramochi

  • 0
    TI__Mastermind 49896 points

    Hello Tadahiko,

    The simulation is using a LMV342. The LMV342 will behave differently than a LMV824.

    The LMV824 model is older and models the output impedance as a fixed value, so it may not show an oscillation under all conditions that a read device would.

    But with a 10uF cap directly on the output, I would expect it to oscillate. There needs to be an output isolation resistor (100 ohms to start) between the output and the cap. See the applications section 8.3.1 about driving capacitive load.

    Regards,

  • 0 in reply to Paul Grohe
    Guru 28715 points

    Hi Paul-san,

    Thank you for your help .
    I'm so sorry that I made a mistake to this thread title and the above file.
    I would like to ask about LMV342.
    Can we look oscillation of the LMV342 by TINA-TI?

    ※I have modified this thread title and the sentence from LM824 to LMV342.


    Regards,
    Kuramochi

  • 0 in reply to Kuramochi Tadahiko
    TI__Mastermind 49896 points
    Hello Kuramouchi,

    The answer is basically the same.

    The LMV342 also does not like 10uF directly on the output, and an output resistor is required. The output isolation circuits referred in the above LMV824-N datasheet apps section would also apply to the LMV342.

    The model is also an older fixed Z-out, so it may not model the oscillation under all conditions.

    Start with Riso of about 100 ohms, and Cf of 50pF. The values can be tweaked for best settling in their circuit.

    Regards,
  • 0 in reply to Paul Grohe
    Guru 28715 points

    Hi Paul-san,

    I received an additional request from my customer.

    They are requesting to analyze phase margin and gain margin by  Monte-Carlo  including the external component information.

    They must know probability distribution of phase margin and gain margin.

    Could you support it?

    They are going to provide required information.

    Please let me know if there is lack of the information.

    Best Regards,

    Kuramochi