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BQ25886: bq25886 issue

Terry Liang
Intellectual 1910 points
Part Number: BQ25886
Other Parts Discussed in Thread: BQ25883, BQ25882

When enable charge but battery is not connected. The waveform of bq25886 seems strange. The time axis is 40us. Why the SW switches for about 20us then stops for about 120us and repeat again? It may not be a charge and recharge process. Because the Deglitch time for recharge threshold and charge termination is about 250ms.  It also may not be PFM. Because PFM at light load when battery is below minimum system voltage setting or charging is disabled. I watch the register. There is no fault and the charging state  is CC fast charging. The Vsys and Vbat increases as charge voltage limit increases.


  • 0
    TI__Guru*** 143870 points

    Hi Terry,

    BQ25886 is a standalone boost charger without I2C.  How are you reading registers?

    Assuming you are using the BQ25883, what is the voltage at VBUS and VBAT, the load on SYS and the charge current setting?  Can you provide all of the register settings?

    Regards,

    Jeff

  • 0 in reply to Jeff F
    TI__Intellectual 1910 points

    Hi Jeff,

    I used bq25882 for testing. the testing condition is enable charge but battery is not connected. VBUS is about 5V. fast charge current is 2A. this waveform can be seen at any battery regulation voltage and wide range of load on SYS as long as IINDPM and VBUS OVP is not appeared. I want to know the switching logic at this condition and whether the enable charge status can be kept after battery is removed. thanks! 

  • 0 in reply to Terry Liang
    TI__Genius 10385 points

    Hello again Liang,

    As Jeff mentioned, would be possible for you to send the register output?

    Thanks,

    Ricardo