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LMV321: Output difference

Kuan Wei Chen (Kevin Chen)
Genius 9710 points
Part Number: LMV321


Dear Team,

A negative feedback circuit using LMV321IDCKR (refer to the figure below, and this circuit has been disconnected from the peripheral circuit), VCC+ =
3.3V. When IN+ is approximately equal to the 3.3V input, we measure the OUT (TP349) = 3.25V and 2.67V on the different board.

Do you have any ideas what cause this problem?

BR

Kevin

  • 0
    TI__Guru**** 167546 points

    Kevin,

    This is a common issue due to exceeding the input common  mode range of the op amp. With both inputs above upper mode mode range, the output may either go to high to VOH level (3.25V) or may want to go low, thus making IN- voltage at edge of upper range (2.67V)

    LMV321AIDCKR is next generation LMV321IDCKR and will provide consistent behaviour in this setup.