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Original question:

LMV321: PCN of RevW → Rev.X

LMV321: Open-Loop Output Impedance vs Frequency

K.Yaita
Guru 29720 points
Part Number: LMV321


Hi Team,

The datasheet Revision X shows the following about "Open-Loop Output Impedance vs Frequency" and the output impedance is larger difference with Revision W.
Should we consider Revison X is correct?
In addition, could you tell me why there is large difference between Rev.X and Rev.W?

- Revision X


- Revision W


Best Regards,
Yaita

  • 0
    TI__Guru**** 166486 points

    Yaita-san,

    Revision X chart is correct but it applies to applied latest PCN changes production. Revision W looks incorrect to me even for pre PCN production. The X-axis jump from 1Hz to 1MHz doesn't instill confidence. This is a 1 MHz device, so it is odd to focus from 1 MHz to 4 MHz. The really low values also look suspicious. 

    A zoom in the "W" figure 2 chart shows about 4dB gain loss with a 600 ohm load. That is a about Zo of 350 ohms. That is a number that makes more sense.

    LMV321 is getting a new process and new wafer fab. So there will be performance change. Overall the changes are positive and good.

    If older performance desired then I suggest looking at LMV321-N; it is close match to LMV321 legacy performance.

      

     

  • 0 in reply to Ron Michallick
    Guru 29720 points

    Hi Ron-san,

    Regarding "W" Figure 2 chart, I agree Zo is 350 ohms.
    However "X" Figure 2 is the same as "W" Figure 2 as the following.



    On the other hand, "X" Figure 20 shows the following and Zo is about 1.1k ohms.
    Is the following "X" Figure 20 correct?



    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Guru**** 166486 points

    Yaita,

    The PCN mentioned alternate fab and process. Before PCN, Zo was about 350 ohms After PCN, Zo could be 350 or 1100 ohms. 

    If you have any applications that you would like me to review, let me know.