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BQ79616-Q1: BQ79616-Q1, PWRBIST_FAIL bit =1 during power supply BIST Run at start

Subhash Dhyani
Intellectual 300 points
Part Number: BQ79616-Q1
Other Parts Discussed in Thread: BQ79616

Tool/software:

Dears CC,

 We have run the power supply BIST at start up in the BQ79616-Q1 device and found PWRBIST_Fail Bit =1.

We further diagnosed and checked all the bits from FAULT_PWR1 and FAULT_PWR2 registers and found all bits are 1 accept RSVD bits.

  • CVSS_OPEN        =1
  • DVSS_OPEN        =1
  • REFHM_OPEN     =1
  • CVDD_UV            =1
  • CVDD_OV            =1
  • DVDD_OV            =1
  • AVDD_OSC          =1
  • AVDD_OV             =1
  • RSVD                   =0
  • PWRBIST_FAIL    =1
  • RSVD                   =0
  • REFH_OSC         =1
  • NEG5V                 =1
  • TSREF_OSC       =1
  • TSREF_UV          =1
  • TSREF_OV         =1

as per the data sheet of BQ79616-Q1, page 85

" The power supply BIST forces a failure and ensures the diagnostic path triggers the fault accordingly. A failure
on the BIST run indicates a diagnostic path is unable to trigger in a fault condition. To further examine which
path is unable to indicate a failure, host can set the DIAG_PWR_CTRL[BIST_NO_RST] = 1. This bit disables the
reset step during the BIST run. Re-start power supply BIST with this option enabled. At the end of the BIST run,
examine the FAULT_PWR1 and FAULT_PWR2 registers. Any register flag that remains 0 indicates it is unable to
flag a failure." 

Please suggest what are the possible reasons which makes PWRBIST_FAIL   = 1.

thanks and regards

Subhash Dhyani

  • 0
    TI__Expert 7000 points

    Hello Subhash,


    When you run the BIST, all of those flags should be 1.

    If you disable the reset by writing DIAG_PWR_CTRL[BIST_NO_RST] = 1, you can confirm by reading all the flags like you showed above.

    The BIST cycle should not include the RSVD registers so I don't think this is the issue.

    I would try resetting all faults first (make sure you do not have any active faults), then re-run the test to see if we get the same result. 

    best,

         Quentin

  • 0 in reply to Quentin Silic
    Intellectual 300 points

    Hello Quentin,

     Before BIST run at start, we have disabled the reset by writing  DIAG_PWR_CTRL[BIST_NO_RST] = 1. And  after resetting all the faults we have checked that there is no active fault available. after Running BIST we found  the status of  all the bits  from FAULT_PWR1 and FAULT_PWR2 registers as shown below. 

    • CVSS_OPEN        =1
    • DVSS_OPEN        =1
    • REFHM_OPEN     =1
    • CVDD_UV            =1
    • CVDD_OV            =1
    • DVDD_OV            =1
    • AVDD_OSC          =1
    • AVDD_OV             =1
    • RSVD                   =0
    • PWRBIST_FAIL    =1
    • RSVD                   =0
    • REFH_OSC         =1
    • NEG5V                 =1
    • TSREF_OSC       =1
    • TSREF_UV          =1
    • TSREF_OV         =1

    Here we found PWRBIST_FAIL  = 1 and as per our understanding PWRBIST_FAIL  should be low (PWRBIST_FAIL   = 0).

    Please confirm.

    Thanks and regards

    Subhash Dhyani

  • 0 in reply to Subhash Dhyani
    TI__Expert 7000 points

    Hello Subhash,


    Yes, I believe that PWRBIST_FAIL should be zero since it appears everything executed correctly.
    I will try to confirm on my end. 

    Can you show me the actual readback of the register rather than this list you typed up?
    Also do you have a second device to confirm this condition on as well?

    Best,

         Quentin

  • 0 in reply to Quentin Silic
    Intellectual 300 points

    Hello Quentin,

    The steps we followed are:-

    Step 1 :

    Reset all fault :  0X331

    Value =0XFF

    Reset all fault :  0X332

    Value =0XFF

    Step 2 :

    Read fault summary:  0X52D

    No of registers read = 40 (i.e.  0X52D to 0X554)

    Result = attached file Before_BIST.pdf

    Before_Bist.pdf

    Step 3 :

    BIST PWR RUN :  0X337

    Value =0X03

    Step 4 :

    Wait for BIST to complete

    Read BIST Status :  0X528

    Result : Complete

    Step 5 :

    Read fault summary:  0X52D

    No of registers read = 40 (i.e.  0X52D to 0X554)

    Result = attached file After_BIST.pdf

    After_BIST.pdf

    Please check the attached files and confirm the possible reasons for  PWRBIST_FAIL  = 1.

    Thanks and regards

    Subhash Dhyani

  • 0 in reply to Subhash Dhyani
    TI__Expert 7000 points

    Hello Subhash,

    When you do PWRBIST_NO_RST = 1, then PWRBIST_FAIL will always result with 1

    Best,

         Quentin

  • 0 in reply to Quentin Silic
    Intellectual 300 points

    Hello Quentin,

    thanks for your email reply.

    We found above information in the another TI part datasheet BQ79718, but we are working and data sheet available only for  BQ79616.

    Now as per our understanding with the above statement :

    when [PWRBIST_NO_RST] = 1 and  [PWR_BIST_GO] = 1

    BIST run provides a further debugging option, but the BIST run always results with
    FAULT_PWR1[PWRBIST_FAIL] = 1 even BIST run is now successful.

    Please confirm.

    Thanks and regards

    Subhash Dhyani

  • 0 in reply to Subhash Dhyani
    TI__Expert 7000 points

    Hello Subhash,
    Yes, when PWRBIST_NO_RST = 1, then PWRBIST_FAIL will always be high.

    Best,

         Quentin