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BQ25896: Wake up system after battery has completely depleted

Shiv Agarwal
Prodigy 100 points
Part Number: BQ25896
Other Parts Discussed in Thread: BQ24296

The battery has completely depleted. Vbus is now applied to charge the battery. Will this chip(BQ25896) be able to wake up the system and ensure smooth functioning from then on? We have been using BQ24296 and in this part, after the battery depletes, applying VBUS alone is not sufficient to wake up the system - we have to first physically disconnect the battery and then apply VBUS to wake up the system.

  • 0
    TI__Mastermind 25800 points

    Hey Shiv,

    I am cautious to say that yes, this charger will be able to both charger your battery and provide power to your system.

    However, the configuration of the charger, the design of your system especially on the input side, the system power drawn, and the input power capability of the adapter will all impact the answer to this question.

    The charger configuration determines the DPM thresholds, either through the PSEL pin state or the register configuration of VINDPM or IINDPM

    The system design on the input side tells us the input resistance from your input source to the charger such that voltage drop from the input to VBUS is critical in entering VINDPM.

    The system power will determine whether the previous two statements have any impact.

    And the input power capability will determine whether VINDPM will play a role, based on the previous item about the system load.

    Regards,

    Joel H

  • 0
    TI__Guru**** 169466 points

    HI Shiv,

    I would expect BQ24296 to power up SYS at VBUS plug in even if battery is depleted and cannot supplement.   BQ24296 and BQ25896 behave similarly at power up. The output power of both would only be limited by the input current limit, per the PSEL pin (which sets the start up IINDPM register) or ILIM resistor (which clamps input current limit) or VINDPM if the input source can't supply the input current set by IINDPM or ILIM or as required by SYS. 

    What is the SYS load at startup?  Is it highly capacitive?

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 100 points

    The system load is 100mA Iavg and 2A Ipeak. 
    I have not measured the Iload at Startup. Looks like if we do a soft start up, this controller will pull through. 

    Thanks,

    Shiv