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MAX232: MAX232N - communication problem

GFE Purchasing
Prodigy 10 points

Part Number: MAX232

Dear Technical Support Team,

We have a customer who has reported several problems with our interface board that uses your part number MAX232N, purchased from your TI.com store.  Apparently, we are having communication problems. When the MAX232N was replaced with a different lot, the board worked correctly.

The part exhibiting unstable operation: 4CC9ZYKER.  Is there any report of this batch of MAX232N having any communication problems, quality issues, etc.? 

The MAX232N parts with these markings are operating as expected:  2AAGG8M64 ; 45A5LXM64 .

Awaiting your reply.

Thanks

OK.jpgOK (2).jpg

NOT OK VERSION.jpg

  • 0
    TI__Guru* 81401 points

    Are you able to provide scopeshots of the failure?

    Can you provide a schematic for review?

    Were all units (working and non working) bought from the TI store? If not, were they purchased from a distributor (is so, which one)

    -Bobby

  • 0 in reply to BOBBY
    Prodigy 10 points

    Hi Bobby,

    Thank you for your reply.

    Unfortunately, we do not currently have oscilloscope captures available.

    We have attached photographs of the devices reported by the customer as non-working and working for your reference.

    As background information, we noticed that the installation was using only TX and RX signals between the devices, without a dedicated GND connection.

    RS232 communication normally requires TX, RX and GND.

    Our board :

    Schematic installation from our client:

    In our testing, the communication operates correctly when a proper common ground reference is present.

    Therefore, it is possible that the installation was relying on a ground reference through another path, making the communication more sensitive to electrical tolerances.

    The customer subsequently replaced the original MAX232N devices with another batch of Texas Instruments MAX232N components.

    After the replacement, the communication issue disappeared and all units are currently operating correctly.

    At this stage, we would appreciate your feedback on whether the attached pictures indicate any visible differences between the devices, and whether there are any known manufacturing or batch-related variations that could help explain the observed behaviour

     

    Additional videos showing the issue are available if required.

     Attachments:

    • Wrong_IC– Customer-reported non-working device
    • CORRECT_IC– Customer-reported working device

    Best regards

    Correct_IC:

    Wrong_IC:

  • 0 in reply to GFE Purchasing
    TI__Guru* 81401 points
    GFE Purchasing said:
    At this stage, we would appreciate your feedback on whether the attached pictures indicate any visible differences between the devices, and whether there are any known manufacturing or batch-related variations that could help explain the observed behaviour

    The working IC is from CFAB and the non-working one is from R-FAB.

    So the working one is the pre-PCN device and the non-working is the post PCN device.

    -Bobby