• State TI Thinks Resolved
  • Locked Locked
  • Replies 14 replies
  • Answers 2 answers
  • Subscribers 64 subscribers
  • Views 201 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.

BQ24298: BQ24298 fails to cut-off and damages self in case of Low Battery

Artronifs Engg
Prodigy 80 points
Part Number: BQ24298

Tool/software:

Hello,

We are using the BQ24298 as a battery charger and also for OTG boost conversion. We are seeing all functions working as expected in ideal case scenarios, meaning, the battery charging, auto-cut-off, dynamic power path management and Boost Conversion, etc everything works fine and our software senses low charge and then shuts down the system.

The problem is seen while trying different batteries that if the software fails to turn down the system on low battery conditions for any reasons (faulty battery or improper charge calculations), then the BQ24298 goes on a mission to staying alive and keeping the voltage Vsys ON and in doing so is getting martyred (damaged) as I would like to believe.

We attempted to mitigate this by setting a higher SYSMIN threshold, and stopping my soldier (BQ24298) from getting into an uncalled war (exerting too much), but this hasn’t resolved the issue.

This has now happened in almost 3 prototypes and we need some guidance into solving this. Are there any particular settings that can be applied or an external protection that we should be using with BQ24298 to cut-off. Please point us in to right direction.

Regards,

Arif Gilani

  • 0
    TI__Guru 57321 points

    Hi Arif ,

    What do you mean "the BQ24298 goes on a mission to staying alive and keeping the voltage Vsys ON"?

    Thanks,

    Ning.

  • 0 in reply to Ning T
    Prodigy 80 points

    Hello Ning,

    I meant that bq24298 instead of shutting down itself in events of LOW Battery Voltage, it tries to supply the system. In doing so it draws more current resulting in damaging itself.

    We observed that when the first bq24298 failed it stopped charging the battery, probably the BATFET got damaged. In the second and third case of failure the bq24298 completely stopped functioning, no response and no regulation from input to output.

    Regards,

    Arif Gilani

  • 0 in reply to Artronifs Engg
    TI__Guru 57321 points

    Hi Arif,

    You mentioned "the first bq24298 failed it stopped charging, the second and third case of failure the bq24298 completely stopped functioning". 

    1. Did you notice any physical damages such as one pin shorts to ground?

    2. After the problematic unit is completely shut down (i.e. no VBUS, no VBAT) for a few minutes, then apply valid VBAT and valid VBUS, will the problematic unit work or not?

    Thanks,

    Ning.

  • 0 in reply to Ning T
    Prodigy 80 points

    Hello Ning,

    Thank you for your response.

    Here is my response to your questions:

    1. No there is no short from any pin to GND.

    2. No, in first damage event - the IC was working fine on Battery and VBUS both giving 3.6V on VSYS but there was no charging happening and OTG function also stopped functioning, meaning, Boost function failed. While, in the 2nd and 3rd events the IC is completely non-responsive, meaning, there is no output on VSYS neither with valid VBUS and valid VBAT. But there is no short.

    Regards,

    Arif Gilani

  • 0 in reply to Artronifs Engg
    Prodigy 80 points

    Ning,

    I am more interested in knowing if we should be using any external undervoltage protection with such battery chargers because there could be cases when we would want to use such an IC where there is no host to monitor voltage and to put the IC in shut-down mode. 

    Arif

  • 0 in reply to Artronifs Engg
    TI__Guru 57321 points

    Hi Arif,

    We will get back to you early next week.

    Thanks,

    Ning.

  • 0 in reply to Ning T
    TI__Guru 57321 points

    Hi Arif,

    Using any external undervoltage protection is better.

    Thanks,

    Ning.

  • 0 in reply to Ning T
    Prodigy 20 points

    Dear Ning,

    When you have a chance, could you please take a look at my issue too? I would really appreciate it

    bq24610-charge-current-problem-at-12v-input

  • 0 in reply to Ning T
    Prodigy 80 points

    Hello Ning,

    Yes, I agree additional external protection is a good idea. Can you highlight any application note or a general practice adopted for an external protection against undervoltage.

    But still, the behavior of bq24298 is still a concern for us. Can you confirm if an undervoltage can really damage the IC and there is no setting that can prevent this from happening.

    Regards,

    Arif Gilani

  • 0 in reply to Artronifs Engg
    TI__Guru 57321 points

    Hi Arif,

    External battery protection is from another group. Please submit a new e2e inquiry.

    In general, only overvoltage and overcurrent conditions may damage the ICs. As mentioned earlier, after a problematic unit is completely shut down (i.e. no VBUS, no VBAT) for a few minutes, then apply valid VBAT and valid VBUS to check if the device is really got damaged.

    Thanks,

    Ning.

  • 0 in reply to Ning T
    Prodigy 80 points

    Hello Ning,

    I checked the boards again and found that 1 out of the 3 damaged bq24298 ICs has very low resistance of about 111.2 Ohms. The same resistance is seen even at Vsys pin.

    Does this mean anything? I am keeping this inquiry open for now.

    Thanks for directing me to another group. I will post a more insightful e2e inquiry like you suggested. Any special tag that should be used so that it goes to the right group?

    Regards,

    Arif

  • 0 in reply to Artronifs Engg
    TI__Guru 57321 points

    Hi Arif,

    Do you observe SYS pin to GND resistance about 111ohm on failed devices? It's better to measure the device pin 2 pin resistance after it is removed from the board.

    The device part number determines the supporting group.

    Thanks,

    Ning.

  • 0 in reply to Ning T
    Prodigy 80 points

    Hello Ning,

    Yes, the measurements are done after isolating any further circuit connected to the concerned pins. The same is also confirmed after removing the IC from the board. The SYS and BATT pins have 111.2 Ohms w.r.t GND.

  • 0 in reply to Artronifs Engg
    TI__Guru 57321 points

    Hi,

    What about SW pin to ground resistance and BAT pin to SYS pin resistance?

    Thanks,

    Ning.