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BQ25890: Input current limit setting

liping pan
Intellectual 650 points
Part Number: BQ25890

When the adapter is connected, we don't need to do any register writing to change the limit setting based on below description, right?

If it's detected as USB DCP, the current limit setting will be changed to 3.25A automatically, right?

My battery is 12000mAh / 3.7V.

If I only need to do 0.2C charge, it seems I don't to do any setting through I2C interface.

It should works fine just based on default setting, right?

I even don't need to feed watchdog as default setting works.

Do I need to anything to handle any default or not?

  • +1
    TI__Mastermind 22175 points

    Hi liping,

    1) When the adapter is plugged in, the input current limit will be set by D+/D- input detection automatically. For USB DCP you will get an input current limit of 3.25A which is enough to meet your 0.2C charging current target. However, keep in mind that the input current limit will be the lower value between the IINLIM setting from USB DCP and the ILIM pin setting. To make sure the physical ILIM pin does not limit your input current, you will need to connect this pin to GND since the ILIM enable bit is set to "1b" by default.

    2) The default charging current is set to 2.048A which seems to be lower than your 0.2C charging target (2400mA based on a 12000mAh battery). If you want the charging current to reach 2.4A you will need to change the fast charging current setting through I2C.

    Also, the default charging voltage limit is 4.2V which is higher than the 3.7V of your battery spec. The charging voltage target can only be lowered via I2C.

    3) If you plan to only use default settings and stay in default mode, the watchdog does not need to be serviced by a host (host mode).

    Please double check all default register settings in Section 9.4 of the datasheet to make sure that your application needs are met. OTG mode must be enabled via I2C if you plan to use the boost converter output.

    Regards,

    James