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BQ24040: Using two battery charging ICs

darren reis
Intellectual 385 points
Part Number: BQ24040
Other Parts Discussed in Thread: BQ25505

Right now we charge our device using the BQ24040, it accepts a USB cable.  It runs nicely.  Now I'm thinking about introducing solar charging on the device so the idle mode can be offset by solar power.  I have been reading the datasheet of the BQ25505, which seems to be a good option.  Now my question is, do I need both ICs?  Is there an app note showing how to have both functionality, charge by USB and supplement quiescent and sleep mode power drain by using the 25505?  

Thanks,

Darren

  • 0
    TI__Guru* 75656 points
    Hello Darren
    It may be possible to connect the output from both devices to the battery then use voltage on USB bus to disable BQ25505 ( /EN ).
    When USB is present the BQ24040 would charge the battery and BQ25505 is disabled.
    No USB present BQ24040 is disabled with solar cell present BQ25505 will operate and charge the battery.

    Let me know if this is the type of solution you are looking for?
  • 0 in reply to Bill Johns
    Intellectual 385 points

    Bill,

    Thanks for the suggestion.  That does sound like what I was picturing.  Is that not a common configuration?  Are there any example designs or app notes demonstrating this arrangement?  


    Thanks,

    Darren

  • 0 in reply to darren reis
    TI__Guru* 75656 points
    Hi Darren
    We do not have a demo circuit for this one.
    Another engineer did test using EVMs and test results looked good.
    Care will need to be take on the USB to EN pin connection to protect from voltage conditions. Abs_Max on the EN pin is 5.5V.