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LMZ31710: Why was PCB land pattern example changed between the device datasheet of 2021 version and 2023 version?

Kazuya Nakai59
Guru 21675 points
Part Number: LMZ31710


Hello guys,

One of my customers is evaluating LMZ31710 for new products using PCB land pattern example which shown on 2021 version of LMZ31710 datasheet.
But when they checked the latest datasheet. they found the PCB land pattern was changed on the datasheet from 2021 version.
At this moment, they have the following questions. Also I attached 2021 version of the device datasheet.
Could you please give me your reply?

Q1.
When was PCB land pattern example changed?

Q2. 
Why was PCB land pattern example changed?

Q3. 
Is no problem to use 2021 version of PCB land pattern example?

Your reply would be much appreciated.

Best regards,
Kazuya.

lmz31710_210122.pdf

  • 0
    TI__Mastermind 18370 points

    Hi Kazuya,

    According to the best of my knowledge, the last time the LMZ31710 datasheet was revised is on May 2020.

    Here is a cut and paste from the datasheet on TI.com.

    I am the application engineer supporting LMZ31710, and I am quite sure it was not changed during the last two years.

    Regards,

    Yitzhak Bolurian

  • 0 in reply to Yitzhak Bolurian
    Guru 21675 points

    Hi Yitzhak,

    Thank you very much for your reply.
    I know that specification on datasheet was not changed.
    But PCB land pattern examples on last part of each datasheet are different.

    Could you please give me your answer to my questions?

    Thank you again and best regards,
    Kazuya.     

  • 0 in reply to Kazuya Nakai59
    TI__Mastermind 18370 points

    Hi Kazuya,

    Can you send us the two versions of the datasheet that you are referring to?
    According to what I know, nothing has been changed after May 2020.

    Please follow the land pattern available on TI.com.

    Regards,

    Yitzhak

  • 0 in reply to Yitzhak Bolurian
    Guru 21675 points

    Hi, Yitzhak,

    The previous version datasheet has already been attached to the begin of this thread with file name "lmz31710_210122.pdf".
    Could you please take a look PCB land pattern example in the datasheet. it is different from the example of the latest datasheet.

    Your answer would be much appreciated.

    Thank you very much and best regards,
    Kazuya. 

  • 0 in reply to Kazuya Nakai59
    TI__Mastermind 18370 points

    Hi Kazuya,

    I have started to investigate the reason for the changes between the two.
    Will hopefully have an educated answer for you by Friday May 26th.

    Regards,

    Yitzhak

  • 0 in reply to Yitzhak Bolurian
    TI__Mastermind 18370 points

    Hi Kazuya,

    I have discussed this with the product engineering department.
    The datasheet on ti.com is the one to follow, otherwise     we cannot guarantee optimal results.
    The datasheet that you have attached seems like a preliminary version.
    The one on ti.com is a lot more detailed and has better recommendations for soldering.

    Regards,

    Yitzhak

  • 0 in reply to Yitzhak Bolurian
    Guru 21675 points

    Hi Yitzhak,

    Thank you very much for your reply.

    I told your answer to the customer. After that, I got the following questions.
    Could you please give me your reply?

    Q1.
    What does mean the optimal results. Which parameter was improved with new PCB pattern?

    Q2. 
    In case of the old version, which parameter get worse compare with the new version PCB pattern case?

    Thank you again and best regards,
    Kazuya.

  • 0 in reply to Kazuya Nakai59
    TI__Guru 56985 points

     

    Today is a US holiday, so I am assisting Yitzhak while he is on holiday.

    The updated recommended PCB land area has slightly smaller PCB land areas that more closely match the dimensions of the pads on the LMZ31710 module.  These tighter PCB pads reduce the positional skew of the LMZ31710 during solder reflow, improving manufacturing reliability and reducing the possibility of solder bridging under the LMZ31710.

    In addition, the updated land pattern reduces thermal impedance by moving the recommended Pin 42 thermal vias inside the land area.

  • 0 in reply to Peter James Miller
    Guru 21675 points

    Hello Peter,

    Thank you for your reply.
    I understood that LMZ31710 temperature in operation might be changed between OLD PCB pattern and New one.

    Could I ask you an additional question?

    Q. Is there any big difference of LMZ31710 electrical characteristics and performance as a power supply between OLD PCB pattern and New one except the device temperature difference?

    Thank you again and best regards,
    Kazuya.

  • 0 in reply to Kazuya Nakai59
    TI__Mastermind 32400 points

      

    None of  the revisions of the datasheet revision update the electrical characteristics and performance of the device, so the answer is no difference between the two, 

    Thanks! 

    Tahar