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BQ24160: Fault using IN src around 75% charge

Tim W
Prodigy 20 points
Part Number: BQ24160
Other Parts Discussed in Thread: BQ500212A

When using the IN source I see faults at just below 4.1V.  About 75% capacity.  My charge current is 300mA.  It will charge for some number of seconds(3-20) then fault and repeat.  The net effect is a very slow charge.  If I drop the charge current to anything lower the process is similar but the charge/discharge ratio is fairly even and it just hovers at 75% capacity.  When I use the USB source my current is above 500mA and charging appears just fine.

I'm unclear why it faults on the IN source.  When the battery is below the 75% threshold I can drop the current as long as I stay above the 75mA threshold mentioned as the current sink for the IN source.  Charging works normally until I hit just below 4.1V. It seems close to the DPPM threshold of 4.2 so I suspect that is related but I'm not sure.


Even when I have a >300mA IN source why does the current drop so much to cause continuous faults? 

  • 0
    TI__Guru*** 149365 points

    Hi Tim,

    What fault is being reported, IN Supply fault? If IN drops to 4.1V and VINDPM is set to 4.2V, the charger thinks the input source is not valid.  How much current is the power source on IN capable of supplying?  If lower than the input current limit setting (1.5A or 2.5A), IN voltage crashes and the charger reports a fault.  The USB input input has lower input current limit settings.  Keep in mind that the total input power must be greater than the BATREG=4.2V * (ISYS +IBAT). 

    Regards,

    Jeff

      

  • 0 in reply to Jeff F
    Prodigy 20 points

    Thank you.  Yes, it is the IN Supply fault.  My IN supply maxes out at ~330mA.  

  • 0 in reply to Jeff F
    Prodigy 20 points

    And I was unclear in my description I think.  The 'just below 4.1V' I mentioned is my battery voltage.  ~4030mmV - 4050mV.  When my battery charge hits around here the faulting starts.

  • 0 in reply to Tim W
    Prodigy 20 points

    I can set it the 330mA 40%, 50%, 60%, 90% and 100%.  All these start faulting at the same place(~4050mV) battery charge

  • 0 in reply to Tim W
    TI__Guru*** 149365 points

    Hi Tim,

    IN supply fault only occurs if IN collapses below VINDPM.  Do you have an oscope that can monitor IN and BAT voltages (and currents too if possible) real time?

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 20 points

    I imagine I can have one of my coworkers set that up for me.  I'll work on making that happen

    I would like to add if I change the VIN-DPM Voltage/ DPPM Status Register from 0x00 to 0x03. The faulting will stop.  That is to say if I start charging and then hit the faulting point I change this register from 0x00 to 0x03 the faulting stops.  Wouldn't this cause the faulting to happen earlier?  I thought this was an offset from 4.2V and 0x03 would move that up 4.44V so that it would fault sooner but it instead seems to prevent faulting.  

  • 0 in reply to Jeff F
    Prodigy 20 points

    After a short time I noticed the: '1 – VIN-DPM mode is active' is now set too.  I don't believe I've ever seen this go high

  • 0 in reply to Tim W
    TI__Guru*** 149365 points

    Hi Tim,

    You are correct. Perhaps your power supply can't function if its pulled below 4.44V and so when the charge reduces its input current to prevent IN from dropping below 4.4V, the power supply can handle it?

    Rgards,

    Jeff 

  • 0 in reply to Jeff F
    TI__Guru*** 149365 points

    Hi Tim,

    VINDPM active means the VINDPM feedback loop is in control and limiting he input current to the converter.  Charge current is deducded to provide SYS load current.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 20 points

    For reference the IN is coming from a bq5102x for the rx side.  My wireless charger uses a bq500212a for tx side

  • 0 in reply to Tim W
    TI__Guru*** 149365 points

    Hi Tim,

    I don't directly support the BQ5102x rx devices but I recall that they have a hard cutoff when you exceed their max output power.  So, you either want need to set VINDPM higher than that cutoff or set input current lower than their max output power.  But, IN input current limit options are only 1.5A nd 2.5A. 

    Regards,

    Jeff