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Original question:

BQ25185: BQ25185 Vin check

BQ25185: BQ25185 Charging Current

Frank LAI
Prodigy 50 points
Part Number: BQ25185

Tool/software:


Vin=12V 2A
Vset=13K
ISET=375R
Battery 3.3V
Why is the VBAT_CHG charging current 50-100mA?

Frank

  • 0
    TI__Expert 8315 points

    Hi Frank,

    Given that VIN is 12V, it's possible the device is entering thermal regulation (TREG) and reducing the charge current to prevent overheating.

    Could you please test with a lower input voltage, such as 5V, to see if the issue goes away?

    Best regards,

    Alec

  • 0 in reply to Alec Lehman
    Prodigy 50 points

    Hi, Alec:

    I can normally supply 800mA using 5V.
    Now I want to use a 12V 2A power supply to charge (at 800mA).
    How can I make it charge properly at 800mA?

    Frank

  • 0 in reply to Frank LAI
    TI__Expert 8315 points

    Hi Frank,

    Thanks for checking.

    I recommend either:

    1. Using a buck converter to step down from 12V before supplying VBUS

    2. Using a switching charger, which is more efficient than a linear charger at higher input voltages

    Due to the nature of the linear topology, power dissipation increases as the voltage drops across the internal FETs and current increases.

    Refer to section 8.3.7.6 of the BQ25185 for more details on power dissipation.

    Best regards,

    Alec