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BQ25120A: How to set fast charge current in the range of 50mA to 60mA

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Replies: 1

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Part Number: BQ25120A

Hi Team,

We met a issue to set the charge current between 50mA to 60mA,such as 55mA

But there is no choice to set 55mA in Fast Charge Control Register;

Here is the setting :

    {BQ25120_STATUS_SHIPMODE_REG, 0x01},
    {BQ25120_FAULTS_FAULTMASKS_REG, 0x00},
    {BQ25120_TSCONTROL_STATUS_REG, 0x88},
    {BQ25120_FASTCHARGE_CTL_REG, 0x88},
    {BQ25120_CHARGETERM_I2CADDR_REG, 0x82},
    {BQ25120_BATT_VOLTAGE_CTL_REG, 0x78},
    {BQ25120_SYSTEM_VOUT_CTL_REG, 0xAA},
    {BQ25120_LOADSW_LDO_CTL_REG, 0x7C},
    {BQ25120_PUSH_BTN_CTL_REG, 0x68},
    {BQ25120_ILIMIT_UVLO_CTL_REG, 0x12},
    {BQ25120_BATT_VOLT_MONITOR_REG, 0x00},
    {BQ25120_VIN_DPM_TIMER_REG, 0x32},

After failing to set 55mA by register,we try to set current by external resistor,and only change register BQ25120_FASTCHARGE_CTL_REG to 0xFC;

The external resistor on ISET is 3.6KR;

The external resistor on IPRETERM is 4.99KR;

Then we test the fast charge current is 55mA;

But we meet another issue that the current can not be terminated even battery reach to 4.2V;

Could you share some tips to resolve this ?

Thanks & Best Regards

Wayne

  • Hello,

    It is correct that the only way to get exactly 55mA ICHG is through the external resistor setting.

    When in external ISET, you also have to configure precharge current for that. Look at the footnote on page 39 of the datasheet on how to configure the precharge current register (0x04) for the precharge current you want

    Regards,

    Sharafadeen Raheem

    Applications Engineer

    Battery Chargers

    Please click "This resolved my issue" button if this post answers your question.

    Check out TI’s new Advanced Linear Charger with 16-bit ADC & LDO

    http://www.ti.com/product/BQ25155

     

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