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SN75HVD1176: What is the cause of the different transient response of the chip between the different lot of production.

YONG HOON KIM
Prodigy 100 points
Part Number: SN75HVD1176

We have used this IC in the production model.

One device gives good performance of rising and falling response like within 1nsec. But the other device of the different lot gives very poor response like 8nsec.e have tested the two different chip within the same circuit.

Is there any issue of the different lot variances.

Thank you.




Attached image shows the test condition and the results. Left one seems normal and the right one is abnormal.

  • 0
    TI__Guru 62920 points
    Hello Yong Hoon,

    Some variation is to be expected from chip to chip, although I am also a little surprised by the amount of difference shown in your screenshots. Can you also please look at the "A" and "B" signals individually on the same screen (rather than just the difference between them)? That may give us a better understanding what is going on. Also, can you please tell us the markings on the top of each chip?

    Thank you,
    Max
  • 0 in reply to Miguel Robertson
    Prodigy 100 points

    Hello Max,

    The two screen shot of the above is the same condition in both time and amplitude scale. so I just think you can compare it directly.

    But we will make a measurement as you requested and will send you the result.

    The ic on the left measurement is as follows.

    VN1176

    11M

    A1JK

    And the right on is

    VN1176

    52M

    A6FHG4

    Thank you.

    John Kim

  • 0 in reply to YONG HOON KIM
    TI__Guru 62920 points
    John,

    Thanks for the info. Are you sure on the markings for the second unit? When we trace that lot number, it actually returns a different device (indicating that the code is invalid). You could take a picture of the device as well if it is difficult to resolve the text.

    Thanks for looking into the individual waveforms as well. I agree that the above screenshots give a good comparison between devices, I just wanted to verify that both devices are giving a symmetrical output or if there were any strange behavior isolated to an individual pin (A or B).

    Regards,
    Max
  • 0 in reply to Miguel Robertson
    Prodigy 100 points

    Dear Max,

    Thank you for your confirmation. It is very unbelievable for the fake or un-registered product code.

    We have to check the way of purchasing this fake.

    Thank you again.

    Best regards,

    John Kim

  • 0 in reply to YONG HOON KIM
    TI__Guru 62920 points
    Hi John,

    While we have seen counterfeit parts on the market before, it is also possible that the numbers on the package were just not very clear. If you want us to trace down any other lot codes (for example, if you are unsure of any of the characters in the code) just let us know.

    Max