• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 1401 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ78350-R1: Device DF was broken after device shutdown

Sake
Prodigy 160 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQ76930, BQSTUDIO, BQ78350

Dear all,

I'm working at production of 6s-4p Lithium ion battery pack with BQ78350-R1 and BQ76930.

When we're producing battery pack at our mass production line, some of devices showed SMBus communication error.

Our production process are followings.

1. to write our DFI file to target PCM and conduct function tests

2. to assemble PCM and battery cell (core pack assy.)

3. to conduct core pack function tests

4. after core pack tests, to send shutdown command via SMBus.

5. then, to assemble final pack and conduct final inspection.

6. at the procedure 5, we found SMBus communication error.

Error information and our investigation results are followings.

1. SMBus communication error means RSOC shows 771% and other command codes can't recieve.

　※see attached image1

2. The failure IC can overwrite FW by BQSTUDIO.

3. After overwrite FW and our DFI, we send shutdown command, but same failure was found.

4. to import srec from failure IC and compare with srec which is before break, 256 byte data seems to be changed to erased state(0xFF).

　　※see attached image2, left:failure right:normal 

5. These failure were found at only specific IC lot 6AK-AC02. We found this failure total 20 of 480pcs. All failure are same phenomenon.


How can I solve it?

image1: registers value

image2: srec_diff    left: failure  right: normal

  • 0
    TI__Guru 54715 points
    Hi Sake,
    It seems part of the flash memory is corrupted as you show.
    There would seem to be 3 possible causes for the situation:
    The bq78350-R1 looses power during an update at shutdown.
    The bq76930 boots during shutdown causing the bq78350-R1 part to start when power is not available
    The VCC of the bq78350 does not transition through the reset level cleanly.
    The first 2 would not seem likely in a battery assembly since the cells are present to provide power as needed. For the third check that the power transitions cleanly during shutdown with the power bus in the BMS board.
  • 0 in reply to WM5295
    Prodigy 160 points

    Hi WM5295,

    Thanks for reply.
    I checked above three possibilities but there are no observation of abnormal power transition.
    So I tried two experiments.

    1. to mount failure IC to EVM board.
    → same failure was observed.

    2. to write FW:BQ78350-R2 to failure IC.
    → failure was not observed with over 100 times of shutdown. then back to write FW:BQ78350-R1, same failure was observed with few times shutdown.

    in conclusion, this failure is dependent with FW revision not of our PCM construction.
    In the sluubd3c, following article was confirmed. Is there any relationship to this failure?

  • 0 in reply to Sake
    TI__Guru 54715 points
    Hi Sake,
    The "Error" file pictured above shows part of the flash erased. That would not be from a check sum calculation. Most likely the -R2 is loading the supply differently as the part shuts down. If you believe the part is bad please return a few pieces through the supply channel.
  • 0 in reply to WM5295
    Prodigy 160 points
    Hi WM5295,

    >The "Error" file pictured above shows part of the flash erased. That would not be from a check sum calculation.
    noted.

    >Most likely the -R2 is loading the supply differently as the part shuts down.
    I'm sorry, but I can't understand above comment well.
    Please let me know detail what operating difference are there between -R1 and -R2 at the shutdown timing.
    and
    Is -R2 the solution to this problem?
  • 0 in reply to Sake
    TI__Guru 54715 points
    Hi Sake,
    Either the parts are damaged or have some unusual sensitivity to voltage. It is not expected to have a flash corruption on a custom design or on the EVM. The -R2 is not an intentional fix, and there is no known difference in the shutdown between -R1 and -R2, but there could be different effect on the supply load since the code is executing from a different location perhaps.