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BQ24297RGET schematic review, please

Other Parts Discussed in Thread: BQ24297, BQ24296

Charging_modified.pdf3323.charger.pdfPlease review my schematic.

CPU will monitor the charging status using STAT pin with 3.3V pull-up resistor.

 I2C(SDA,SCL) and INT will connected to CPU with 10kohm and 3.3V pull-up resistor.

 OTG pin needs to be defined. But Buck mode will be only feature to be used.

 BATT(SYS) is the output to be connected to the all inside device.

 QON needs to be defined. Shipping Mode? 

2nd Question on 11/02 to Omid are below.

I have update the schematic. Please review one more time.

1)      I have added 10uF at the SYS pin

2)      I will Keep QON to open condition(NC) and will use plug in adapter to turned on from shipping mode. Is this correct? Does Plug in adapter mean the voltage changing at pin VBUS? So when I unplug and plug the charger to toggling VBUS pin,  is it turned on?

  • Hi Team,

    Can you please review our mutual customer's post.

    Thanks a bunch!

    Respectfully,
    Omid
  • Hey Vincent, 

    As far as I can tell, without seeing the rest of your system, the schematic and your implementation looks correct. Just make sure you follow proper layout techniques and guidelines. 

    Since you are using the bq24297, the OTG pin is only used for switching the part into OTG mode. It seems you are utilizing the D+/D- detection of the part, which handles the USB input limit setting, unlike the bq24296 version that requires both the PSEL and OTG pins to set the USB input current setting. Since you are only using the part in buck mode, you can tied this pin to ground or pull it out from your FAN_EN signal.

    The QON pin can be left floating or tied to ground if not used. Be aware that shipping mode is activated as described by section 9.3.1.2.2 Shipping Mode of the datasheet, and not on by default. In regards to question 2), you are correct. Plugging in the adapter is the same as adding a valid DC source to the VBUS pin. This will turn off Shipping Mode and turn on the BATFET. You can also utilize the other methods in previously mentioned section of the datasheet

    In regards to 1), adding the 10uF is fine. Depending on your output ripple voltage requirements, you may want to increase this value. 

     

    Hope this helps,

    Regards,

    Joel H

  • Thanks for replying so quickly Joel!
  • No problem Omid. Hopefully this assists your customer.

    Regards,
    Joel H
  • Joel,

    Thank you for the answer.
    I have additional question, if you do not mind. I understand rising edge with 2msec high level of QON will turn off shipping mode and turn on BATFET.

    Then if the QON is rising up more than 2msec again during BATFET is turned on condition(normal operation), how the bq24297 will operate?
    Does this QON triggering during turn on condition is ignored by bq24297?
  • Hey Vincent,

    On this part, the bq24297, holding QON longer than the 2ms specified while the device is operating normally with BATFET on has no function.

    As you said, it is ignored by the charger.

    Regards,
    Joel H
  • Joel,
    OK, thanks.

    BR,

    Vincent
  • Joel,

    One more question.
    Can I use bq24297 for charging 3000mAh BL-53YH OEM Battery for LG G3?
    If you can share any example battery that I can charge, it will be helpful for me to decide.

    Best regards,

    Vincent Hwang
  • Hey Vincent, 

    You should be able to use the bq24297 to charge that battery. You can charge any single cell Li-ion battery with that charger. 

    You just need to follow the battery's specification to avoid damaging the battery during charging. All batteries have max charge currents they can handle for charging. 

    Unfortunately, I do not have a database of batteries and their respective specifications, so I cannot provide any insight into a particular example battery. 

    But any single-cell Li-ion battery with a voltage (nominal or max) in the range of 3.504 V – 4.400 V,  should be fine. 

    For testing, I tend to use batteries that have a protector integrated with the pack. 

    Hope this helps,

    Joel H

  • Joel,

    Thank you for the answer. By the way, could you let me know more for the protector? Is this battery only necessary for testing purpose?

    For production, is it not necessary to use the battery with protector?

    what is the protector?

    Your information is very helpful for me to use your chipset.

    Thanks and best regards,

    Vincent Hwang.

  • Hey Vincent,

    Some battery manufacturers have the protector integrated and some don't. Your LG battery most likely has it integrated as it is likely part of the phone's system solution.

    It may not be necessary to use the protector if you are accurately monitoring battery conditions and make sure they fall within spec, BUT IT IS HIGHLY RECOMMENDED TO USE A PROTECTOR to prevent any unknown disturbance that may cause unsafe or damaging internal battery conditions.

    These protector may be just a simple FET control circuitry that monitors battery voltage and opens to prevent a condition like extreme discharge, or they could be more complex systems like TI's Gauging solutions that monitor current, voltage, and other parameters and offer some control features.


    Regards,
    Joel H
  • Joel,

    OK, Thanks . This is helpful

    Best Regards,

    Vincent

  • Joel,

    I am testing BQ24297RGET EVK.

    When I turn on the EVK with 2A USB adapter W/O load and battery. Vsys=4.2V and stat LED is blinking. Is this LED Blinking OK?

    By GUI, VSYS = unregulated.

    Best Regards,

    Vincent

  • Hey Vincent,

    At what frequency is the LED blinking? This can be easily measured on an oscilloscope with a probe at TP10 (STAT).

    If the LED is blinking at 1Hz, that signifies a fault. If it blinking with a different frequency, it is the device likely switching between Charge Complete and Charge in Progress due to the C11 battery decoupling cap.

    Regards,
    Joel H
  • Joel,

    Blinking is faster than 1sec. So it is not 1Hz.  So I suppose it is charge completed and charge -in progress condition, I think. Thanks.

    I will attach the battery and will monitor again.

    Best Regards

    Vincent