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TPS732: Wrong device marking speculation

Rodrigo Vernini
Intellectual 290 points
Part Number: TPS732

My company was designated to review a medical company PCB.

We discovered that the main issue was the TPS73250DBVT, it had 5,5V as input, and had (5,5V-dropout) in the output, it should be a fixed 5V regulator.

This problem happened with all 14 PCB's, analyzed, 3 regulators each, and we didn't see any potencial cause for those regulators been burnt, futhermore it hadn't any shorted pin.

We worked in the possibility of that component to be wrong, and we tested for TPS73201 responses:

1) Short between OUT and "FB" = 1,2V

2) Tested some resistors dividers they all matched the theoretical output value from TPS73201.

Everything was compatible!

We bougth new TPS73250DBVT, and everything worked fine.

The problem was, the "device mark" was T41 (Fixed 5,0V).

The only visible difference was that the regulators that was responding as the adjustable had a mark in it's botton "89P1", as the new fixed ones didn't have any. 

The question is, can those fixed regulators, in a specific situation of incorrect use, be sistematically transformed in the adjustable regulator? Or it was a fabrication mistake from TI? We still have all the regulators that was removed fom the PCB.

We are in a big dispute with the assembly company for the cause of this problem, and we need a response from TI.

  • 0
    TI__Expert 7015 points
    Hi Rodrigo,

    Would you be able to provide some more information about these devices that were supposed to be fixed, but came out as adjustable? Do you have any of the lot information that should be printed on the reel that these device came on? The T41 marking is the topside marking for the fixed 5V regulator, but I cannot find any reference to a top or bottom side marking of "89P1". If you would be able to help us get the part number and a picture of the reel label I can help better trace where these devices came from.

    Regards,
    Mark
  • 0 in reply to Mark Sellers
    Intellectual 290 points

    Hi Mark,

    i took some photos of the TPS:

    Top VIew:

    Botton View:

    And uploaded a video on youtube:

    In the video i'm shortening output with NR/FB and it works exactly like the adjustable TPS. Without the short circuit the output is less than 0,5V the input, i suppose it's just the circuit dropout.

    Protoboard photo:

    Dropout photo:

    I'm waiting the assembly company to send the the reel information, i haven't found any information about the botton code, but i thought it was some kind of productioin traceability.

  • 0 in reply to Rodrigo Vernini
    TI__Expert 7015 points
    Hi Rodrigo,

    It looks like this could potentially be a counterfeit device. I have attached a link to our anti-counterfeit policy www.ti.com/.../anti-counterfeit.html

    If you are able to get a picture of the reel information I will be able to confirm this for you.

    Regards,
    Mark
  • 0 in reply to Mark Sellers
    Intellectual 290 points

    Hi Mark,

    thanks for the reply.

    We still don't have any response from the assembly company.

    Is there any way to confirm this without the reel information? Can you confirm that TI doesn't have any TPS732 with that mark on the botton? Can i have some official report from TI about this device? I could send samples if needed.

    Many thanks again.

  • 0 in reply to Rodrigo Vernini
    TI__Expert 7015 points
    Hi Rodrigo,

    There are some TPS732 that do have a bottom side marking, but the bottom side marking is not specific to a single voltage version. In order to figure out if this device should have had a bottom side marking we will need the reel information. If you would like to return the parts for further analysis more information can be found on that here: www.ti.com/.../customer-returns.html

    Regards,
    Mark