• State Resolved
  • Locked Locked
  • Replies 16 replies
  • Answers 5 answers
  • Subscribers 64 subscribers
  • Views 685 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.

BQ24160: the definition of weak source

Polly Chung1
Intellectual 2110 points
Part Number: BQ24160

Dear team,

My customer found a power supply have charging issue and charger would show “weak source”, however, no definition for “weak” source in datasheet, could you help clarify this definition? Thank you.

Best Regards,

Polly Chung

  • 0
    TI__Guru**** 167196 points

    Hi Polly,

    Datasheet section

    9.3.16.3 Bad Source Detection

    explains hour bad (weak) source detection functions.  The V(BADSOURCE) threshold mentioned is the current VINDPM setting.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 220 points

    Hi Jeff

    So, suppose the weak input source is V(UVLO=4V MAX) < Vin(weak source) < V(INDPM=4.28V, set by I2c), right?

    Thanks.

    George

  • 0 in reply to George Yang2
    Prodigy 220 points

    Hi Jeff

    More questions, summarized :

    1. Suppose that weak input source is V(UVLO=4V MAX) < Vin(weak source) < V(INDPM=4.28V, set by I2c), right?

    2. Any way to ignore the "weak source" or "Vin<Vuvlo" event by charger and keep charging? (would not implement, just a workaround for further testing)

    3. If have the inrush current cause the Vin drop to under Vin(DPM), what the width of the pulse to trigger the fault event?

       (EX : Vin<Vin(DPM) keep >0.5ms? or >1ms?)

  • 0 in reply to George Yang2
    TI__Guru**** 167196 points

    HI George,

    RE1: The weak source threshold referred to in the datasheet as VBADSOURCE = VINDPM setting.  If the input voltage droops to VBADSOURCE=VINDPM, input current is effectively reduced to 0 A.

    RE2:  There is no way to ignore VIN<UVLO.  To prevent inrush current from causing momentary droop you could try lower input current and/or charge current setting initially then increase in I2C later.

    RE3:  Deglitch for bad/weak source detection is 32ms.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 220 points

    Hi Jeff

    We found the high inrush current when "start charge", higher inrush current with lower Vbat...

    Sometimes, the inrush current cause the input power as weak or bad source, then stop charging...

    Want to confirm with you have the soft-start between VAC&VSYS or VSYS&VBAT on bq24160?

    Any idea to reduce the inrush current? Any register setting to improve?  (Our charging current : 700mA ; Vindpm: 4.28V)

  • 0 in reply to George Yang2
    TI__Guru**** 167196 points

    Hi George,

    The buck converter that provides SYS (and therefore BAT through the BATFET) has soft start at power up.  Bad source detect only occurs during the first 30ms after IN/USB rises above UVLO.  It does not happen when you enable charge or incur a load transient after power up.  Can you provide a scope shot of input voltage, input current, VSYS and ISYS when this occurs?

    Regards,

    Jeff

     

  • 0 in reply to Jeff F
    Prodigy 220 points

    Hi Jeff

    The inrush current when starting charging and load by battery, as below figure, it seems positive correlation with the delta VINDPM and VBAT.

    So, higher inrush with lower Vbat...

    BR,

    George

  • 0 in reply to George Yang2
    TI__Guru**** 167196 points

    Hi George,

    Your figure did not come through.  But, in summary, the IC will behave differently at lower battery voltages:

    VBATUVLO=2.5V < V(BAT) <VBATSHRT=3.0V - Icharge=ISHORT=50mA so I would not expect inrush caused by battery current

    V(BAT) < VBATUVLO=2.5V - No supplement mode so if your ISYS is large at power up, the battery is not available to supplement

    If the battery is above 3.0V then I recommend either disabling charge or lower ICHARGE at start up.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 220 points

    Hi Jeff

    The inrush current (from charger to battery) we measured is 1.5A when battery ~3.4V, and 1.1A when battery ~3.9V.

    (Charge current : 700mA, system load ~200mA)

    And the VAC voltage might drop to 4.1V sometimes, that would trigger the protection by charger and stop charging.

    That's the problem we want to fix.

    Maybe the volatge drop also relate to the output cap in adpater, however, we want to find out the solution by charger, and it is better to implement with SW solution(ex. register setting).

    Thanks.

    George

  • 0 in reply to George Yang2
    Prodigy 220 points

    Hi Jeff

    I have attached the figure in before reply.

    Do you have any idea the improvement by register setting?

    Thanks.

  • 0 in reply to George Yang2
    TI__Guru**** 167196 points

    Hi George,

    Can you modify the software so that

    1. charge is disabled at IN/USB attach

    2. charge is initially < 500mA then raise to higher later

    2. input current is initially < 500mA (or the lowest you can use and still keep system up) then raise higher later

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 220 points

    Hi Jeff

    When Vin is weak source, the charger would turn off the gate between Vin and Vsys.

    And will re-try per 1~2 second?

    Also, some behavior when Vin is < VUVLO?

    Thanks.

    George

  • 0 in reply to George Yang2
    TI__Guru**** 167196 points

    George,

    If weak source, the charger turns off Q1, the FET between IN/USB and PMID, which is the input to the buck converter.

    Yes, if weak source is detected, the charger will retry every 1-2 seconds until a good source is attached.

    No, if input is below UVLO, the charger is disabled and will not retry.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 220 points

    Hi Jeff

    We still some questions about the weak source detection.

    [Q.1] 

    1-a. 32ms deglitch time, this 32ms is used to confirm the input source is good source and keep >32ms?

    (It means the input should be > Vindpm(4.2V default) and over 32ms?)

    1-b. Or, 32ms deglitch time, this 32ms is used to confirm the input source is bad source and keep >32ms?

    (It means the input is weak/bad if Vin < Vindpm(4.2V default) and over 32ms?)

    Which description is correct for 32ms deglitch time?

    [Q.2]

    If description '1-a' is correct, the charger how to confirm the Vin is weak source? The mosfet would be turned off "once" the Vin<Vindpm?

    Thanks.

    BR,

    George

  • 0 in reply to George Yang2
    TI__Guru**** 167196 points

    George,

    Regarding 1, if the source voltage is still below VINDPM after 32ms, a weak source is detected.  This gives time for transient dip to correct itself.

    Regarding 2, n/a since 1b was correct.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 220 points

    No more questions. We can close this issue.

    Thanks, Jeff.