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[BQ24168] No return to normat from battery fault status

Chang-woo YANG
Expert 1285 points
Other Parts Discussed in Thread: BQ24168

Hello~

Connect the AC adapter to system, and then when testing the experiment for remove & mount of the battery (several times for short periods of time), sometimes charger status does not return to normal from battery fault.

It used almost fully charged battery products in the experiment.

In the general case, when remove the battery from system, FAULT bits of Status/Control register is setting to "111".  And then, FAULT bits are returning to "000" after remounting the battery.

If the malfunction, FAULT bits does not go to "000" even if battery is remounting to the system.  So, to solve this problem (to clear the FAULT bits), HZ_MODE bit has control (HZ mode enable --> HZ mode disable).

But this solution also has one problem, when HZ mode is active and the battery is removed, the system is turned off.

Even if Connect the battery, why does not clear the FAULT bit??  I want to know the reason.

In addition to controlling HZ_MODE bit, do you have another solution?

Does it have the minimum required time interval to remove the battery and connect it again?

I attached the schematic of BQ24168.  Please check the schematic, too.

Thanks... C.W. :)

  • 0
    TI__Guru*** 147775 points

    What is the battery voltage at removal?  What is the VBATREG? 

    When removing the battery, you should get a Battery Not Present fault and VBATREG resets to default value of 3.6V.

    When replacing a battery with VBAT < VBATREG=3.6V, charging should resume and the fault should clear.

    When replacing a battery with VBAT > VBATREG=3.6V, fault changes to BAT_OVP and will not clear until you change the VBATREG value to be greater than VBAT.

    The IC needs to complete one battery detect cycle (~250ms) in order to enter a known state.  You can confirm that this is the issue by disabling termination, which disables battery detect.  

    I am unable to reproduce this issue on my EVM because I cannot remove and replace that fast with my current setup.

  • 0 in reply to Jeff F
    Expert 1285 points

    Hello~

    Thanks for your answer.

    I have one more question about your reply.

    As you said, "The IC needs to complete one battery detect cycle (~250ms) in order to enter a known state.  You can confirm that this is the issue by disabling termination, which disables battery detect."

    Does "by disabling termination" means TE bit of internal register 02??

    If yes,

    If TE bit is setting to "0", it means disable the battery detect cycle, and then it does not detect the OVP??

    Thanks... C.W. :)

  • 0 in reply to Chang-woo YANG
    TI__Guru*** 147775 points

    TE bit is used to enable/disable termination only.  It does not affect battery OVP detect.