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Original question:

BQ25303J: Unknown blink rate and fault

BQ25303J: BQ25303J Battery charger early cut-off issue

Soham Biswas
Prodigy 10 points
Part Number: BQ25303J

Hi,

I am currently using the BQ25303J to charge a 5000mAh Lithium Ion Cell (21700). I have set the VBAT Reg at 4.2 V by connecting VSET Pin to ground using a 0 Ohm Jumper. The battery should charge should 4.2V, but 

the charger is terminating charge at 4.028 V. Can't figure out why it's doing that. Any help would be highly appreciated!

  • 0
    TI__Guru 57341 points

    Hi,

    Could you please describe how did you measure the terminating charge voltage?

    Thanks,

    Ning.

  • 0 in reply to Ning T
    Prodigy 10 points

    Hi Ning,

    I was am using a bench top Regulated Power Supply to test the charger. I could monitor how much current the IC was pulling. Once the current started reducing and eventually reached 0 Amps, I noticed that the charge LED had turned off indicating charging had completed. After this I checked the Battery voltage using a Multimeter.

  • 0 in reply to Soham Biswas
    TI__Guru 57341 points

    Hi,

    Once the charge current drops to 0A, the line voltage drop between the BAT pin and the battery terminal also drops to 0V. To observe the terminating charge voltage, please record the BAT pin voltage right before the charge current drops to 0A from the charge termination current.

    Thanks,

    Ning.