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TL331-Q1: Different performance with different LOT

Andy Jin
Prodigy 250 points
Part Number: TL331-Q1
Other Parts Discussed in Thread: TL331, LM339

Hi expert, 

Our customer bought 5Kpcs TL331QDBVRQ1, but 90% failed in the function test. But this did not take place before. Compared the difference, these parts have different topside marking. It means they are assembled in different assemble site. 

  • 0
    Prodigy 250 points

    Please help check the schematic, is anything need to improve? 

  • 0
    Guru 270510 points

    Please show an oscilloscope trace of pins 1 and 4.

    I suspect that you get oscillations because of missing hysteresis. If this is the case, add positive feedback, e.g., 100 kΩ between OUT and IN+.

  • 0
    TI__Guru 52726 points

    Hi Andy,

    What is failing? What is the input signal amplitude and speed?

    As Clemens said, a scope photo of the input signal and output would be helpful. As well as a better description of the problem.

    A photo of any box or reel labels would also be helpful.

    From the schematic, I do not see anything glaring. Threshold is 400mV, as long as the input signal is below 3V, there should not be any problems.

    The TL331 is under PCN to change the die. Please see the LM339 family Application note, section 2.1:

     Application Design Guidelines for LM339, LM393, TL331 Family Comparators

    There should only be one marking for the TL331QDBVRQ1, and that should be "T1RU". Both look to be 'T1RU".

    The little marks near the edges are a binary date code. Both devices are from 2023, the "OK" is from May, and the "NG" is from September (older). The photo is not quite good enough to read the secondary date code reliably. We would need the lot# to confirm, but I am guessing that the newer  "NG" device is the new die. See section 3.5 of the appnote for known differences.