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BQ25896: Input current limit verification.

Part Number: BQ25896

Hi ,

we are using BQ25896RTWR for battery power management. we have set the input current limit to 500 mA by connecting external resister (787 ohm) at ILIM pin.

Here my question is, How to verify that the IC actually draws the current set by ILIM pin?

  • Hi Priyanshu,

    The BQ25896 has a built in ADC that can track the charge current. The charge current information is stored in REG12[6:0]

    Note that the ILIM pin does not control the charging current, it only acts as an input current limit when enabled by REG00[6] = 1b (default setting). Also, if the IINDPM current limit setting (REG00[5:0]) is lower than the ILIM pin setting, the charger will use the lower IINDPM value instead of the ILIM pin.

    The charging current is set by the Pre-Charge current limit register (REG05[7:4]) or the Fast Charging current limit register (REG04[6:0]).



  • Hi James,

    Thank you for your reply.

    I tried to read the charge current information stored in REG12[6:0]. The value received is 0.

    I also read the Note mentioned in the datasheet is "This register returns 0000000 for VBAT < VBATSHORT".

    When i measure voltage (VBAT) manually on the PCB it gives me 3.9V.

    Could you please help with this?

    Other information:

    I tried to read several other resister listed below.

    REG06 -> 0101 1110  ( 94 dec)

    REG0E -> 0000 0000

    REG05 -> 0001 0001 (17 dec)

  • Hi Priyanshu,

    Check to see if the ADC is updated with the most recent values. Be default, the ADC is set to 1-shot mode so it only records the first set of values it detects when the BQ25896 is powered up.

    You can either set REG02[7] = 1b to activate a single conversion from the ADC or you can set REG02[6] = 1b to have the ADC do continuous 1-second conversion. Read the registers after setting one of these options.