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BQ25887: BQ25887 Schematic Check

Sean Kovacs
Prodigy 130 points
Part Number: BQ25887

Could I get a review of the 2 cell charger schematic using the BQ25887 please?
BATT is the positive side of the 2 cell battery and BATT_MID is the middle connection between the 2 batteries. 
I do not plan on using the SNS/SYS output, so a lower capacitor was used. 

  • +1
    TI__Mastermind 33605 points

    Hello,

    My schematic review is as follows:

    1. I see you are limiting the cell balance current to 382 mA typical. Please keep in mind maximum of 400 mA.

    2. The maximum output sink current for PG/, STAT, and INT/ is 6 mA. With a 470 Ohm Pullup with 5 V, the current when on is 10.6 mA which will damage the device. Please use the recommended 10 kOhm resistor.

    3. We recommend a minimum 44 uF capacitor on SNS as it the output of the boost converter. This is a must.

    4. I see maximum ILIM current via ILIM to GND.

    5. I see adapter source via PSEL to GND.

    Regards,

    Mike Emanuel

  • 0 in reply to Michael Emanuel35
    Prodigy 130 points

    That migth explain some things with the readings via I2C. Seemed like the chip was not working okay.. Have some new chips on the way - will update per your suggestions. Heads up for anyone using the Mikroe Balancer 5 - they use 470 Ohm resistors on their PG/STAT pullups. It behaved poorly for me as well, though it kinda worked.  

  • 0 in reply to Sean Kovacs
    TI__Mastermind 33605 points

    I await your response.