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BQ25890: BQ25890 with BQ25731, application questions.

Dave Knight
Intellectual 590 points
Part Number: BQ25890
Other Parts Discussed in Thread: BQ27531-G1, BQ24190, BQ24163, BQ27530-G1

I have questions regarding MaxLife and MaxCharge products for use in a new projection. Project specifications, sketch of block diagram, and questions below. 

  • Project specifications:

 Dual Input Battery pack with low speed data 

Input 1: USB

Input 6-32V unregulated(nominal 24V).

Battery capacity: 1800mAh+. I’d like to have electronics in place to grow to a higher capacity battery pack. My goal is to charge battery quickly, extend number of charge/discharge cycles, and produce least heat.

Output 8-20V.

Data: USB-UART Converter

BOM Cost: $10 @ 1k quantity.

 

  • For battery management, I’m considering the following options

BQ27531-G1 with BQ25890/2

BQ27531-G1 with BQ24190

BQ27530-G1 with BQ24163

What would be the best choice for my application?

 

  1. My understanding is that these chargers have MPPT and such to make charging fast. Is this correct?
  2. Is there anything that makes a 5A MaxCharge charger faster than a 5A non-MaxCharge charger? Do I see charge speed increase with 1800mAh pack, or only with larger packs?
  3. My understanding is that MaxLife fuel gauges automatically direct compatible charger ICs through the entire charge cycle. They also can figure out how battery capacity and health on the fly and adjust charging accordingly. Is this correct? http://newscenter.ti.com/2013-06-06-TI-fast-charge-technology-gets-more-life-out-of-a-Li-Ion-battery
  4. Do MaxCharge charges integrate the MaxLife fuel gauge functions? If not, are they compatible with MaxLife fuel gauge I2C interface? If not, please confirm that code would have to be written to enable this functionality. This article seems to suggest MaxLife and MaxCharge compatibility, but I don’t see any reference to such compatibility anywhere else.
  5. Will these chargers share datalines with a USB-UART converter? I think yes from first response to this post: https://e2e.ti.com/support/power_management/battery_management/f/179/p/509707/2225451?tisearch=e2e-sitesearch&keymatch=maxcharge#2225451
  6. Do MaxCharge chips require special charging port to charge quickly? I’ve read that HVDCP or QC2/3 wall-wart might be needed such as these?
      1. https://www.amazon.com/Charger-Adapter-Portable-Samsung-Motorola/dp/B01AVXL53Q
      2. https://www.newegg.com/Product/Product.aspx?Item=N82E16875939039
  7. Do MaxCharge chips require extra hardware for handshaking?
  8. What other questions should I be asking?

  • 0
    TI__Genius 10240 points

    Hi Dave,

    The MaxCharge is to deliver higher input power to charge a battery when the USB 5V/2A adaptor is not enough. To achieve higher input power with the same 2-A connector or cable, higher voltage such as 9-V or 12-V will be generated after MaxCharger handshakes with adjustable high voltage adaptor (HVDCP). For your application with 1800-mAh battery, higher input power does not bring benefits. You might consider to use bq2419x family for the best thermal performance. Our gauge expert will recommend the gauge for the application.

    Regards,

    Eric

     

  • 0 in reply to ezhao
    Intellectual 590 points

    Thanks for prompt response. I'd like to make design extendable to work with a bigger cell. What capacity cell do we need for higher input power to bring benefit?

  • 0 in reply to Dave Knight
    TI__Genius 10240 points
    9-V is the next voltage level for the HVDCP above 5-V. You might want to use the high input voltage handshaking when the input power needs to be above 5-V x 2-A = 10-W and as high as 9-V x 2-A = 18-W.
  • 0 in reply to ezhao
    Intellectual 590 points
    ok. about 4500mA would benefit from HVDCP.
    Is this the only advantage of MaxCharge, or does the charging profile change somehow, like using higher current when the battery is deeply discharged?

    The last sentence in first replay to original post says your gauge expert would recommend the right gauge for the application. When will I get this recommendation? Right now my plan is to pair BQ27531-G1 with BQ24190.
  • 0 in reply to Dave Knight
    Intellectual 590 points
    Actually, will the BQ24190 charge 1800mAH any faster than BQ24163? I think the 1800mAH will want to be charged at 1.8A or less, so the BQ24190 shouldn't have any advantage except running a little cooler.

    BQ27530-G1 with BQ24163 might be best. BQ24163 has dual inputs which handles power or-ing for me.