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SN74LV161A: Quality issue

Danilo A.
Mastermind 34480 points

Part Number: SN74LV161A

Hi Team,

Posting on behalf of our customer.

I will share this E2E post to our customer so he can reply when needed.

I have attached both images. The top image is from the new production (new code) and the bottom image is from the old production (old code).

This is a series device since 2022.

The device exhibits significant speed fluctuations, especially at 1000 rpm.

We have equipped approximately 20 circuit boards with the old production (old code) and the error has been fixed.

The question is: Does the new production (new code) that we are now using come from TI?

I would be very grateful for your feedback!

SN74LV161APWR.pdf 

Regards,

Danilo

  • 0
    TI__Mastermind 33515 points

    Hi Danilo,

    Does the customer have the shipping label? I can't identify either device from the top marking alone.

    Best,

    Malcolm

  • 0
    Guru 326450 points

    New devices might be more sensitive to violations of the ∆t/∆v limit or the VIL/VIH thresholds. Please show an oscilloscope trace of a rising edge of the CLK signal.

  • 0 in reply to Clemens Ladisch
    TI__Mastermind 34480 points

    Hi Malcolm, Clemens,

    Thank you for your response.

    I have shared this thread to our customer so he can continue the communication with you.

    Regards,

    Danilo

  • 0 in reply to Danilo A.
    TI__Mastermind 34480 points

    Hi Malcolm, Clemens,

    For some reason, our customer can't reply to this thread. Please see his response below.

    I recorded the rise of the CLK signal. The site isn't working well; I couldn't update my email address.

    I don't have a shipping label. I have an HS code from the new IC version, which is: 8542399000.

    Regards,

    Danilo

  • 0 in reply to Danilo A.
    Guru 326450 points

    This looks OK.

    What exactly do you mean with "speed fluctuations"? Does it count too fast or too slow? Can you show the input and the wrong output together on the oscilloscope?

  • 0 in reply to Clemens Ladisch
    TI__Mastermind 34480 points

    Hi Clemens,

    Please see our customer's response below.

    Thank you for your efforts

    The speed fluctuation also occurs at low speeds. I assume this is mainly due to the control system giving me the wrong number of pulses.

    I have recorded a recording of the outputs in the MCU (see image). A is LSB.

    The CLK signal is a representation from the MCU. The shape can be misleading Blush

    My next step would be to display the CLK and the outputs on an oscilloscope.

    Regards,

    Danilo

  • 0 in reply to Danilo A.
    TI__Mastermind 34480 points

    Hi Clemens,

    I recorded the signals as shown in the figure.
    Blue =CLK
    Yellow = QA
    Purple = QB
    Green =QC
    neither the frequency nor the duty cycles are right for the signals.
    I thank you for your efforts and look forward to an answer

    Regards,

    Danilo

  • 0 in reply to Danilo A.
    Guru 326450 points

    The counts are 6→1→2→4→5→7→0→2→3→5→6→0→1→3→4→6. Apparently, some clock edges are doubled (or tripled).

    As far as I can see in the image, there is no decoupling capacitor near the supply pin. It is possible that the new die is more sensitive to the unstable supply and has internal oscillations.