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Original question:

BQ24075: Not charging!

BQ24075: battery is not charging

Yi-Shiun Wu
Prodigy 10 points
Part Number: BQ24075
Other Parts Discussed in Thread: BQ27441-G1,

Hello,

I have design the following schematic to charge my battery. However, my battery is not charging although the LED connects to \CHG is lighting up. P2 connects to the battery and P3 connects to 5V charging input. Is there any place that I connect them wrong? Thank you!

  • 0
    TI__Mastermind 23170 points

    Hi,

    Welcome to E2E!

    Are you able to communicate with the BQ27441-G1 gauge and see the charge current or battery voltage? Can you measure the voltage of the battery when you see this and the ISET voltage when you see no charge?

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 10 points

    Hello

    This is what I got from BQ27441-G1:

    state-of-charge (%): 34%
    battery voltage (mV): 3782 mV
    average current (mA): 0 mA 
    full capacity (mAh): 1126 mAh
    remaining capacity (mAh): 374
    average power draw (mW): 0 mW
    state-of-health (%): 93%

    voltage at ISET is 447mV

    Thank you!

  • 0 in reply to Yi-Shiun Wu
    TI__Mastermind 23170 points

    Hi Yi-Shiun Wu,

    Am I correct in that your ISET resistor is a 590k resistor? The valid resistor range is 590 Ohm to 8.9kOhm. Was the intention a 590 Ohm resistor?

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 10 points

    Hello,

    Thank you for finding this bug! However I replace the ISET resistor to 1.5K Ohm and it is still not charging. From the BQ27441, I am still reading 0mA. Thank you!

  • +1 in reply to Yi-Shiun Wu
    TI__Mastermind 23170 points

    Hi,

    Taking a second look at the schematic I do notice a lack of a minimum 4.7-uF capacitor on the BAT pin of the BQ24075. Are you able to add a capacitor there and see if the charge changes?

    Would you be able measure the following voltages for me (waveforms preferred):

    • VIN of BQ24075
    • VOUT of BQ24075
    • VBAT of BQ24075

    The following measurements would also be great

    • voltage at the TS pin of the BQ24075
    • voltage at the SYSOFF pin of the BQ24075
    • voltage at the ISET pin with the 1.5kOhm resistor that you mentioned

    Are you also able to provide a register dump of the BQ27441?

    Best Regards,

    Anthony Pham