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BQ24232: Advice needed on Li-Ion Battery Charger System using BQ24232 and BQ27441

TitoZ
Prodigy 100 points
Part Number: BQ24232
Other Parts Discussed in Thread: TPS61241

Hi everyone,

I am currently working on a Li-Ion battery charger system for my senior design project. I dont have much of a power electronics background so I would like some advice/help on a couple things. 

Some background: A single Li-Ion battery will need to power a raspberry pi 4 which requires 5V that will run multiple Bluetooth modules. The project needs to be portable, so that is why we also need a battery charger system. I have attached a picture of a high level view of what the charger system should contain. 

I did some research and I am considering to use the BQ24232 as the battery charger and BQ27441 as the fuel gauge. Since the raspberry pi needs 5 V to operate, I believe I will need a boost converter and I was considering the TPS61241. However, a concern I have with the boost converter is, since I will be boosting the voltage and I have a fixed load, that means my current will also increase. If the current increases the battery will not last as long. In order to avoid this problem, I am currently doing research on the mAh rating I should obtain for my battery, but I was also wondering if there are boost converters that take this into consideration? 

I would like to know if my considered options would be good options for this project, or if there are any other recommendations. 

In addition, I am planning to simulate my battery charger circuit, are there any recommendations of what software to use for that? The only circuit design software I have used in school is Multisim. 

Any help would be greatly appreciated!

  • 0
    TI__Mastermind 23410 points

    Hi Tito,

    Welcome to E2E! If you're considering a large battery such as 3000mAh, do consider the time it will take to charge and the recommended charge current for the battery as instructed by the battery datasheet. The BQ24232 is a 0.5A power path charger. Our linear charger options go up to 1A charging and so you may want to go to a switching charger for higher current if that's desired. 

    I can move this to the boost converter team if you have more questions but if you are setting the boost converter to 5V anyway, the RPI4 will only take as much current as needed. Are you referring to the current being pulled by the buck converter from the BQ24232 when in battery only mode?

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 100 points

    Thank you for your help Anthony,

    I am going to run some simple test on the RPI later today to see an idea of how much current I will be needing. I dont want to get a battery that is way bigger than what is actually needed. For some more background, part of the project is to connect multiple Bluetooth speakers to the RPI (up to 5 speakers), so I will be utilizing a USB hub and multiple Bluetooth dongles. 

    To clarify, the BQ24232, will only provide a charge current of 0.5A, so as long as the battery I end up choosing requires a charge current of the same value, I should be okay with utilizing that battery charger?  

    I do not believe I am familiar with switching chargers, I will do more research on that, and try to find some on the TI website

  • 0 in reply to TitoZ
    TI__Mastermind 23410 points

    Hi Tito,

    No problem, looking forward to your update on the current consumption of the RPI. And as mentioned previously, if you'd like I can forward this thread to the converters team and they can help with the converter questions.

    TitoZ said:
    o clarify, the BQ24232, will only provide a charge current of 0.5A, so as long as the battery I end up choosing requires a charge current of the same value, I should be okay with utilizing that battery charger?  

    The BQ24232 features Power Path management, a way to charge a battery at the BAT pin as well as provide a voltage rail to power a system if needed at the OUT pin. This means you could power your RPI while also charging your battery at the same time and the IC. The BQ24232 will provide a max of 0.5A but some of this will go to your system at OUT. The charge current for the device can be configured for 25 to 500mA

    Let me know if you have any other questions

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 100 points

    Hi Anthony, 

    So after a lot of research yesterday, the RPI consumes 1.25 A under stress and it suggest to add 1.2 A for USB peripherals (which I will be needing). So to be safe, I want to supply the RPI with 5V and 3 A. So because of this I will believe I will need to use a Li-Ion battery of 3.7 V and at least 4000 mAh so that it can work for at least an hour continuously. 

    Now that I have that set, I believe I will need to get a switching charger, like you mentioned in the earlier post. I will continue to research into possible ones, but if you have any suggestions I would highly appreciate it! 

    In addition, if you could pass this onto the converter group that would great, I still have a concern about the current (from the battery) being way too high once I boost the voltage up to 5V, that will cause the battery to drain too quickly.

  • +1 in reply to TitoZ
    TI__Mastermind 23410 points

    Titoz,

    Apologies, you'll need to start a new thread regarding a DC/DC converter. You'll get a better result that way.

    It does sound though like you may be more interested in a switching charger. If you have any more questions on the BQ24232 feel free to ask here!

    Best Regards,

    Anthony Pham