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Original question:

LMZ13608: LMZ13608TZE/NOPB Shorts occur at pins 6 and 7

LMZ13608: Request the Board Test

SOHEE KIM
Prodigy 30 points
Part Number: LMZ13608

Hello,  

LMZ13608TZE still has problem like CS0481694 , I couldn't find what is the problem.

If we send my whole Board Can you check what 's the factor has caused problem on my board?

I am looking for your reply.

Thanks

  • 0
    TI__Guru 50120 points

    Hi,

    In order to understand if this is a layout issue or device issue is by first getting a LMZ13608EVM and doing a ABBA test.

    This is done by taking the unit on your board, removing it, and swapping it onto the good known LMZ13608EVM to test for basic operation.

    Also take the good known unit on the LMZ13608EVM and swap it onto your board to retest.

    This will provide two datapoint ( 1. failure unit onto known good EVM; 2. good unit onto customer board).

    This way the issue can be narrowed down to either device level of system board level.

    Please do the suggested above and provide feedback on the results.

    Regards,

    Jimmy 

  • 0 in reply to Jimmy Hua
    Prodigy 30 points
    Hello, 
    - LMZ13608TZE* 7760pcs  -> has defective 100 pcs
      Order# T01174691  with T01174694
    - LMZ13608TZE* 600pcs   ->has defective 20pcs
      Order# T01396518
    The defective parts, has Output Lower than 0.8V. 
    The nomal Parts should has Output more than 0.8V
    Could you check what is the problem? 
    Thanks
    Sohee Kim
  • 0 in reply to SOHEE KIM
    TI__Guru 50120 points

    Hi Kim,

    1. Are there any more information to this like lot code, date code, etc.? I might be able to get a customer quality engineer to look at the specific material code and check the history of these parts.
    2. How are teste defective units tested? Are they populated on your board to check for output voltage? If so please provide your schematic so I can review and make sure there aren't any schematic level issues that might be causing this. 
    3. Have you tried doing a ABBA test with a good known EVM yet to confirm this failure is device related? Please provide waveform imagines of VIN, VOUT, and EN when you get the chance.
    4. How long have these units been stored? If they have been sitting around for a long time there may be moisture in the device. I would suggest baking these units for 24 hours to remove the moisture and retest.

    Regards,

    Jimmy

  • 0 in reply to Jimmy Hua
    Prodigy 30 points

    Hi, 


    Are there any more information to this like lot code, date code, etc.? I might be able to get a customer quality engineer to look at the specific material code and check the history of these parts.

    → I bought them on 'TI.com'
    - Order# T01174691 with T01174694
    (Lot 1520 , (D) 2047 )
    - Order# T01396518
    (Lot 1585, (D) 2047+5)

    How are teste defective units tested? Are they populated on your board to check for output voltage? If so please provide your schematic so I can review and make sure there aren't any schematic level issues that might be causing this.

    → When I received the parts, I tested 50 of them with had no problems.
    After done to make all of board, I found the problem with the output voltage being low. (Tested when Part on the Board)
    I checked the schematic with TI customer support and there were no problems.


    Have you tried doing a ABBA test with a good known EVM yet to confirm this failure is device related? Please provide waveform imagines of VIN, VOUT, and EN when you get the chance.
    → Yes, I done ABBA Test and EVM Test.
    I am sorry, I dont have Waveform Imagines. I done for made all my product with re-working .

    How long have these units been stored? If they have been sitting around for a long time there may be moisture in the device. I would suggest baking these units for 24 hours to remove the moisture and retest
    → Due to the short production schedule, the storage time is within 1-2 weeks.

    Thanks

    SOHEE 

  • 0 in reply to SOHEE KIM
    TI__Guru 50120 points

    Hi,

    I'll need to check the the customer quality engineer to see if we can pull anything from that information that you've provided.

    As for the ABBA test, did the failure move with the unit?

    Can you tried to bake the units for 24 hours to remove any potential moisture that is trapped in the device from being left in storage?

    From my understanding if the units are sent in for FA they will first go through me (apps) to confirm basic operation/functional testing.

    1. I will check the unit as is with continuity to see if there are any existing pin shorts
    2. Next I will have the return fail unit soldered onto a good known EVM and test basic operation (startup and steady state)
    3. If there are still issues observed, the units will make it's way through the FA process for further internal investigation.

    Just to help me understand your setup, how have you tested these defective units to know that there are ~100 defective units with low output power? Were test units soldered onto your PCB to test for basic operation? If so, please provide the full schematic so I can review and make sure there aren't any issues with the schematic that might be causing this failed measurement. 

    Regards,

    Jimmy