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BQ25730: Integrated USB C Battery Charging Solution

Part Number: BQ25730
Other Parts Discussed in Thread: TPS92390, BQ25713, BQ25792, BQ25306, BQ25723, , TPS25750, BQ4050, TIDA-050047

Hello,

I am designing a device that will run off 2x 18650 batteries in series (e.g. 7.4V, 2600mAh).  I'm looking to understand if there's any fully integrated solution with USB C PD controller, Battery Charger, and Fuel Gauge.  If not, I'm looking for help in understanding the differences in your product line and your recommendation for my application.

A few specifics about my design:

  • Application: LED lighting (I am considering TPS92390 boost current regulator to drive the LEDs)
  • Max operating power: 15W
  • Battery: 2S 18650 (7.4V, 2600mAh).  Battery pack will include protection circuitry, but temperature sensor will not be fed into our unit.
  • Desired battery charge time < 2hrs.
  • Power path required.  We want to be able to power device from USB regardless of battery state. 
  • As we'd like to provide full power while being able to provide some energy to battery, this is driving the requirement of USB C PD controller as USB C 1.2 maxes at 15W.  I am planning to use a 27W USB C charger setup for 9V,3A.
  • There is no need for our device to supply power out (e.g. OTG).
  • We need to be able to give 20% increments for battery life which I believe would require a fuel gauge to work reliably (please correct me if I'm wrong here).

I have looked at the following parts:

Battery Charger: BQ25306, BQ25713, BQ25730, BQ25723, BQ25703, BQ25792
PD Controller: TPS25750, TPS65987
Fuel Gauge: TPS65987, TPS25750, bq4050

I also found a reference design, TIDA-050047 using BQ25792 with TPS25750.

I understand the BQ25792 has a big difference of integrated FETs, but besides that these parts all look very similar.  I'd appreciate any insight you have into the differences in these parts and what you'd recommend for my application (including any potential insight into chip shortage concern).

Kind Regards,
-Jon

  • Hi Jon,

    Thanks for reaching out.

    First I want to say that this thread spans across different product lines and the scope is a bit big. I would recommend creating different threads and ask product specific questions separately in order to get the maximum support from the product line experts. For example, have one thread for USB C PD controller, one thread for charger, and one for gauge.

    No, I don't think there is an integrated solution combining all 3 areas.

    To answer your questions about chargers:

    1. BQ25306 is a standalone part and a buck (step down from input to charge) charger.
    2. BQ25792 is a buck-boost converter with integrated FETs for an integrated solution and small form factor.
    3. BQ25703 is a older buck-boost controller so it has less features than the newer parts. For example, no VAP mode.
    4. For the rest, they are all newer buck-boost controllers. Please see below.


    Yes, we do have an USB C + battery charger EVM that you can evaluate. 

    https://www.ti.com/tool/USB-PD-CHG-EVM-01 

    Thanks and I hope this helps,

    Peng

    *If my answer solves your question, please press "This Resolved My Issue" on the thread.  

  • Thank you Peng, you've answered my question very well.  I'm leaning towards using the BQ25792 and TPS25750 as is in the reference design.  Just to confirm, the BQ25792 would allow power path (powering device at full 15W and charging batteries at the same time)?

  • Hi Jon,

    Yes, the BQ25792 is a power path part.



    As for whether or not it can support 15 W system power on top of charging the battery, this will depend on your circuit operating conditions (input as well as output). These are the conditions that we recommend for BQ25792:

     (page 8 of datasheet)

    In your case, as your adaptor is 9V@3A, it would be in buck mode most of the time so I think it should be fine. You can refer to some of the efficiency data on the BQ25792 datasheet as well (page 20). I would recommend getting an EVM and test it under your system's worst load conditions.


    If you need higher power than this, I would recommend going for one of the buck boost controllers with external FETs. They can handle very high power. 

    Thanks,

    Peng

    *If my answer solves your question, please press "This Resolved My Issue" on the thread.