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BQ25703A: BQ25703A charge current not stable

Star Xu
Genius 9645 points
Part Number: BQ25703A

Hi

My customer used BQ25703A to charge 3 series cells. It is found that when the charging current set low, for example 704mA, and in the case of low battery voltage,

They found the current fluctuations,Attached the waveform.

CH1:BATT+ current ,CH2:Q4 gate ,CH3:BATT+ voltage

how to improve this problem?

Thanks

Star

  • 0
    TI__Mastermind 33445 points

    Hi, Star,

    When the charge current is less than 1A, the current sense signal is low. The charger operates in light load conditions. In light load, the charger operates in PFM mode to achieve the best efficiency possible. You may observe pulse-skipping or elevated current ripple. As load current increases, the charger operates in PWM mode. The current ripple will decrease accordingly. This is usually not a concern. 

    You may operate in low switching frequency or change the current sense to 20mohm.