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TM4C123 Chip Failure

Greg Leeson
Prodigy 120 points
Other Parts Discussed in Thread: TM4C123GH6PZ

We are experiencing random failures of the TM4C123GH6PZ on our custom board.  We have scrupulously analyzed all circuits for scenarios that might stress the TM4C, especially power on/off.  We have run tens of thousands of power cycles in an attempt to uncover some failure mechanism.  All to no avail.

A chip that has failed will not communicate over JTAG and, interestingly, the TDO pin shows a square wave with a period in the 60-70ms range.  We have accumulated a number of failed chips.  Is there a way they can be analyzed (by the manufacturer) to give an indication of the failure mechanism?

  • 0
    TI__Guru**** 244440 points
    Hello Greg,

    I believe this a revision 6 silicon and you are using EEPROM. There is a known errata where EEPROM usage during a power cycle may cause the device to become inoperable. The TDO pin showing a square wave of 60-70ms indicates that it has failed initialization and is an indication of the EEPROM errata.

    You may have to go through the errata to implement the WA's (though it is not possible with the device locked out) or switch to revision 7 silicon which has this issue fixed.

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Guru 47900 points

    Amit Ashara said:
    switch to revision 7 silicon which has this issue fixed.  

    Glad to have "caught" this post.

    Two (natural) questions arise:

    • how do we detect Rev 7?
    • is Rev 7 the normal/customary stock @ hobby distys?   (Digi-Key, Mouser, Farnell)

    This detail renders your alert more usable...

  • 0 in reply to cb1
    TI__Guru**** 244440 points
    Hello cb1,

    The marking on the package will tell if it is rev 6 or rev 7. Both Rev 6 and Rev 7 are available on distributor sites. They would be TM4C123GH6PZI/TM4C123GH6PZI6R and TM4C123GH6PZI7R for rev 6 and rev 7.

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Guru 47900 points
    Hi Amit,

    Thanks for that - hopefully benefits several - we note that our devices are (all) Rev 6. (Ratz)