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BQ2057W: Charge Controller compatible with 2s2p battery

Ryan Amyette
Prodigy 30 points
Part Number: BQ2057W
Other Parts Discussed in Thread: BQ2057, , BQ24004, BQ24133

For a school project, part of our tasks include charging a lithium ion battery. The battery pack we have is an RRC 2057 2s2p and was wanting to check and see if I could use the bq2057w as a charge controller for a 2s2p battery. Am planning to design circuit based on figure 1, page 7 on the bq2057 datasheet. However, was planning on using a 62.5 mOhm resistor to set charging current at 2 A and a BDP 948 PNP transistor. 

Thanks for the help,

Ryan

  • 0
    TI__Guru* 75656 points

    Hello Ryan

    The BQ2057W design is older than you are and I do not recommend it.  External current sense resistor and pass fet make it high parts count and low efficiency.

    For linear try the BQ24004, this is a 1A also but in single package.  May want to try to charge below 1A to better manage thermal rise on device.

    The pack is 2S2P, and I am guessing the capacity is 4.0mAh or greater?  You can charge this with linear (1A) but it will take a while.  A switching charger can deliver more current at higher efficiency.

  • 0 in reply to Bill Johns
    Prodigy 30 points

    Hello Bill,

    Yes, the battery is rated for 6400mAh. We've had issues with charging so at this point, even if it takes the battery a while, would like to demo the battery at least charging. I have one of the BQ2057W devices on hand at the moment, so I may try to test charging with that for a little bit while waiting for the BQ24004 to arrive. 

    Thanks for your assistance,

    Ryan

  • 0 in reply to Ryan Amyette
    TI__Guru* 75656 points

    Hi Ryan

    Also for this large a pack, 6400mAh charge current provided by linear charger (1A) is a little low.  Switcher would be a better fit.  One unit to take a look at is the BQ24133 it can be configured to charge two cells with higher current.