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BQ24160: Safety timer fault issue

Zoe Ko
Expert 3810 points
Part Number: BQ24160

Hi team,

We have safety timer fault issue as below.

For my understanding, there is no delay required of the BQ24160 after 128us pulse in STAT pin to read FAULT values.

  1. In the normal case, if the safety timer fault happened, charging disable set by charger itself or disable by SOC sending command from I2C?
  2. The STAT pin measured as below, when the safety timer fault happened, AC line power still connected, the STAT will change keeping low after ~398ms, and charging continuously.

a) Two 128us pulse?

b) Why not keep Hi-z after the 128us pulse? Reset by host or charger itself? (Not remove AC line power)

Thanks.

  • 0
    TI__Guru**** 165766 points
    Hi Zoe,

    When the safety timer expires, charging should automatically stop with the CE bit changed to “1", the VBATREG and charge current registers reset to the default values, and STAT and INT issue a single 128 us pulse and then go HiZ. Charging should not restart unless the registers are changed? Can we get a register dump before and after the events above?
  • 0 in reply to Jeff F
    Prodigy 50 points

    Hi Jeff

    According to the figure attached before, timer fault happened only ~398ms and charging continuously, we can't dump register within 1s...

    Still have below questions :

    1. In the measurement attached before comment, two 128us pulse(high-low-high), any idea about this? 

    2. By your comment, the STAT pin change keeping low after 398ms and charging continuous, this should be reset by host(SOC)? Any alternative causes?

    Thanks.

    George Yang

  • 0 in reply to George Yang63
    TI__Guru**** 165766 points

    Hi George,

    The first INT pulse could be the safety timer expiring and the second could be charge restarting.  Charge can only be restarted by an external event like input or BAT remove/replace, toggling the /CD pin or the host resetting /CE bit to 1.  Even when restarted, the charge voltage and charge current registers are reset to defaults.  Can you confirm that the registers before and after this event (not necessarily within 1s) are different?

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 50 points

    Hi Jeff

    As below log, dump charger regiater, and we found the safety timer fault and CE bit change to 1(disable). But resume to charge within ~1 seconds...

    1. Does it resume by OS(host send command)? Charger would not resume charging by itself when fault event happen?

    2. In the datasheet, the 128us INT from charger STAT to host, any debounce time need if SW want to read the fault status?

    (in the measurement attached before, the first 128us pulse comes after fault event about 150us)

  • 0 in reply to George Yang63
    TI__Guru**** 165766 points
    HI George,

    The charger should not resume charge after safety timer fault because CE bit is disabled. The host could have to write to the CE bit to restart charge.

    Once the INT pulse occurs, the status registers have been updated.

    Regards,
    Jeff
  • 0 in reply to Jeff F
    Prodigy 50 points

    Hi Jeff

    We will also confirm with SW the process when INT pulse occurs.

    However, could you comment about the question 2, any debounce time needed if SW want to read the fault status?

    (In the measurement attached before, the first 128us pulse comes after fault event about 150us)

    Thanks.

    BR,

    George

  • 0 in reply to George Yang63
    TI__Guru**** 165766 points
    Hi George,

    I do not know the delay time between fault and INT pulse. The expectation is for the SW to monitor for the INT pulse and then read the register.

    Regards,
    Jeff
  • 0 in reply to Jeff F
    Prodigy 50 points

    Hi Jeff

    This delay time is normal or abnormal?  If it is does happen everytime the fault event occur, no requirement for this delay time? Maybe SW need some debounce time to read the register.

    Thanks.

    BR,

    George

  • 0 in reply to George Yang63
    TI__Guru**** 165766 points
    George,

    The delay time is expected. If you are not going to use the INT as the trigger for reading the register, then I suggest adding a debounce to the SW in the range that you measured.

    Regards,
    Jeff