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BQ25887: disabling ICO

Part Number: BQ25887

Hello Guys,

Good day.

Is it possible to set the maximum Input Current manually of this device? Customer cannot use the maximum input current and so would like to disable the ICO (Input Current Optimizer).

Thanks!

Art

  • Hi Art,

    Yes.  If PSEL=low and ILIM pin is disabled (REG01), the IINDPM register auto sets to 3.0A. The host can also I2C write directly to the IINDPM register (REG03). ICO, if enabled in REG03, only activates if VINDPM activates.  VINDPM activates when the voltage at VBUS droops to the VINDPM threshold due to a weak power supply or resistance (thin traces/wires) from the power supply to VBUS pin.  If ICO is activating, you can disable it but VINDPM has also activated and will reduce input current in order to prevent the charger from collapsing the input power supply.  You can lower the VINDPM threshold (REG02) but that will lower input voltage point and therefore input power and output power.

    Regards,

    Jeff

  • Hello Jeff,

    In addition, customer mention that he have indeed disabled the ILIM pin by setting the EN_ILIM bit to 0 from REG01. He just noticed that it also has this strange behavior. When he set it to 0 it will automatically reset back to 1 shortly after setting the bits even when there is no power adapter plugged in. He have provided a video of this.

    If you watch closely to the Charger Current Limit byte logged in the video, the EN_ILIM bit jumps to 1 in the end of the video for some unknown reason. Same happens with the AUTO_INDET_EN bit (REG06) in the Charger Control 2 byte.

    2021-01-20 12-17-01.zip

    Thanks!

    Art

  • Hi Art,

    The EN_ILIM (as well as some registers) auto reset when the watchdog timer expires.  Is your customer writing to the watchdog timer bit to let the know charger know that the host is up and running?  If not, they either need to do that or disable the watchdog timer.

    Regards,

    Jeff

  • Hi Jeff,

    When the watchdog timer expires, the charger enters Default mode. Is there any way to change the default values?

    Thanks!

    Art

  • Hi Art,

    Unfortunately, no.  The default values are set during production.

    Regards,

    Jeff