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Original question:

BQ24259: can we set charging current at 2.5A in bq24259?

BQ24259: shipping mode design

Brian Chan
Expert 4320 points
Part Number: BQ24259

Hi Team

I have two question about shipping mode design.

1.During shipping mode,the output VSYS should be change to 0V,how about VBAT?

2.For shipping mode exit,should be trigger by QON signal as below info,but MCU is power from VSYS?So how to design this shipping mode exit?

BRs

Brian

  • 0
    TI__Genius 13905 points

    Hi Brian,

    Brian Chan said:
    1.During shipping mode,the output VSYS should be change to 0V,how about VBAT?

    Since shipmode is entered while a battery is present, VBAT should be equal to the battery voltage. It is the BATFET disconnecting that separates VSYS from VBAT.

    Brian Chan said:
    2.For shipping mode exit,should be trigger by QON signal as below info,but MCU is power from VSYS?So how to design this shipping mode exit?

    This is ultimately application dependent so it may vary. A typical way in which this is achieved is through a hardware pushbutton that pulls QON to VBAT. In the final use, when a button is pressed for 2 ms the device will be enabled and then the MCU receives power. In the application, is shipmode exit determined only by the MCU?

    Best Regards,

    Juan Ospina

  • 0 in reply to Juan Ospina
    TI__Expert 4320 points

    Hi Juan

     Thanks for your feedback.For this project,we don't have extral button to trigger.Only way is using CH_SRC to trigger charging ic to exit shpping mode.Here is logic Pega want to implement,because shipping mode is factory mode,so after factory final test,MCU will inform to charging IC by I2C interface to let system enter into shipping mode.When end user get system,they need charging system first time to let system resume from shipping mode.But after this time,the shipping mode will be never be triggered.

    Please help check this method if can workable for your IC.If can workable,only need connect to QON of charging IC to CH_SRC signal.Thanks!

    BRs

    Brian

  • 0 in reply to Brian Chan
    TI__Genius 13905 points

    Hi Brian,

    I believe this could work. Some things to take into account are the 2mS requirement for shipmode exit, the -0.3 to 7V limits of the QON pin, the 1.3V Input high threshold of QON, the 8uA leakage current of the QON while high, and the 1 MOhms pull down resistor internal to QON. As long as these are compatible with your input voltage then I believe it should work as a solution.

    Best Regards,

    Juan Ospina