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PMP41115: Charger and BMS IC recommendation

Samo Smodiš
Intellectual 362 points
Part Number: PMP41115
Other Parts Discussed in Thread: BQ25756, BQ76907

Tool/software:

Hi,

We are designing a battery charger and BMS to charge Li-ion 7s2p cells. The battery pack charger must accept USB PB 3.1 (240 W) and safely charge the cells. The BMS must oversee that charging, balancing, and protect the cells with standard protections (UV, OV, OC, OT..). Ideally the charger and BMS ICs are stand-alone and do not need a MCU host to configure and operate. The charging proces must simply start when the USB PD 3.1 source is present and end when the cells are fully charged. The battery pack supplies power to a LED load when not charging. The load is powered directly from the battery pack (no need for USB OTG).

An additional point to consider is the fact, that we are very limited with total PCB space so a solution that meets all of the requirements at minimal PCB area is prefered.

Here is a list of the system requirements:

1. Charger accepts UCB PD 3.1 240 W and any lower version of PD.

2. Protects the cells againts damage with standard protections (UV, OV, OC, OT...)

3. Powers a LED load and safely cuts off battery power when battery voltage falls below a safe limit.

Thank you for your recommendations!

Regards,

Samo

  • 0
    TI__Expert 6670 points

    Hi Samo,

    I am not sure what you question is? I think the reference design should meet your requirements, but it needs to be verified by you.

    Thanks,

    Robert 

  • 0 in reply to Robert Taylor1
    Intellectual 362 points

    Hi Robert,

    I want to hear recommendations for charger IC and BMS IC. The reference design is charging only.

    Additionaly, the reference design states the the charger supports charging 10~12 cells. My application has 7 cells in series, so I am asking if this will work with 7 cells as well.

    Regards,

    Samo

  • 0 in reply to Samo Smodiš
    TI__Expert 6670 points

    Hi Samo, you can still use the same charger IC that is in this design BQ25756, it will work with 7 cells also.

    Thanks,

    Robert 

  • 0 in reply to Robert Taylor1
    Intellectual 362 points

    Ok, thanks. Do you have any suggestions on how to implement the BMS?

  • 0 in reply to Samo Smodiš
    TI__Expert 6670 points

    The BQ25756 takes care of all of the charging algorithm. Also has the following features:

    Integrated 16-bit ADC for voltage, current, and temperature monitoring

    • High safety integration – Adjustable input overvoltage and undervoltage protection – Battery overvoltage and overcurrent protection – Charging safety timer – Battery short protection – Thermal shutdown

    • Status outputs – Adapter present status (PG) – Charger operation status (STAT1, STAT2)

    What other features do you need? Second level protection? I think the BQ device will address all of your concerns.

  • 0 in reply to Robert Taylor1
    Intellectual 362 points

    Thank you for your suggestion. Looking at the BQ25756 it only provides voltage and current protections on the whole battery pack, not on the individual cells. I also did not notice that it support cell balancing which is a fundamental feature of the BMS. The voltage and current protections work by disabling the buck-boost fets, but this serves no purpose since the load in my application is connected directly to the battery pack and not through the buck-boost stage as in the case of USB OTG.

    Therefore I still need a way to implement cell protection features (OV, UV), cell balancing, and battery pack voltage and current protection. Thats why i am asking for a BMS IC recommendation.

  • 0 in reply to Samo Smodiš
    TI__Expert 6670 points

    We have a reference design that offers all of those features, but requires a MCU. Please check out

    https://www.ti.com/tool/PMP23329

    We also have some devices like BQ76907 that might work for your application.

    Thanks,

    R2