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BQ24232: issue on charging

Michael Akiva
Prodigy 10 points
Part Number: BQ24232

Tool/software:

Hi, 
I am using the BQ24232 charger 
I have this schematics - 

 sometime it charges at 200mA, sometimes the module doesnt even charge. 
I do get power at VCHG and VDD1, I do have power at VBAT, but no current is going to the battery. 
When I try to discharge it, they all work perfectly fine.  Only the charging is making me an issue. 

I did test the on about 10 new PCB's, and about 30% of them don't charge my battery. 

I tried to charge all of them with the same battery so its not a battery issue. 

Hope to receive your feedback

Regards,

Michael. 

  • 0 in reply to Michael Akiva
    TI__Expert 8395 points

    Hi Michael,

    Thanks for reaching out. I've reviewed your schematic, and it looks good, so we can proceed with debugging the issue you're experiencing. Please see my comments below:

    • OUT (2x 4.7uF), BAT (2x 4.7uF), and IN (1uF + 100nF) each have the required capacitances.
    • EN1 is tied to GND and EN2 is pulled up to OUT, so ILIM is set by the RILIM resistor.
    • TS is tied to GND through a 10k resistor to maintain a valid voltage on this pin
    • /CHG is pulled up to OUT through an LED and 1k resistor. Please note that this pin can sink a maximum of 15mA, so ensure that the current-limiting resistor is selected accordingly to stay within this limit.
    • /PGOOD is floating, which is fine since it's an open-drain output.
    • Using KITERM=0.03A (typical), RTERM=3.57k, and RISET=4.32k, ITERM is calculated to be 25mA.
    • Using KISET=870A*ohm (typical) and RISET=4.32k, ISET is calculated to be 201mA.
    • Using KTMR=48s/kohm (typical) and RTMR=56.2k, t_MAXCHG is calculated to be 7.5 hours.
    • Using KILIM=1530A*ohm (typical) and RILIM=3.01k, ILIM is calculated to be 508mA.
    • There's a diode OR circuit on IN.

    If I understand correctly, the issue is that there's no charge current flowing to the battery on a few of your boards. Could you please answer the following questions to help me better understand the issue:

    • What is the measured VOUT when this issue occurs?
    • What is the measured VIN on the cathode side of the Schottky diodes?
    • Is the /CHG LED on when this issue occurs?
    • Is there a system load connected to OUT? If so, how much current is it pulling?
    • You mentioned that there's still power at OUT when this issue occurs. What is the measured VOUT, and is any downstream load connected to OUT able to pull current?

    Best regards,

    Alec