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BQ25710: battery charging system

Lucas Della Santina
Prodigy 35 points
Part Number: BQ25710
Other Parts Discussed in Thread: BQ25730, BQ34110,

Good evening for everyone.

I am currently in the research stage, to later implement a battery charging system (for an application where the battery is rarely discharged).

The battery pack wiil be PbA.

First of all, I'm looking to use BQ25710 (SMBus) or BQ25730 (I2C), battery charge controllers. Is it correct to use bq34110 as the battery gas gauge, connected to the battery charger controller? Any other recomendations?

Thanks in advance, hope you can help me.

  • +1
    TI__Mastermind 33445 points

    Hi, Lucas,

    I don't have any recommendation since the battery gauge is not my focus area. I would suggest you reposting this thread using the battery gauge BQ34110 as reference part number. 

    Regards,

    Tiger

  • 0 in reply to Tiger Zhou
    Prodigy 35 points
    Thank you very much, I will follow your advice
    I also wanted to ask if there are any libraries available for RTOS, the idea of this charger is to use it in an embedded system (for example es32), from what I understand in my case lear acid charger, I would have to change certain parameters of cc and cv to that it works.
  • 0 in reply to Lucas Della Santina
    TI__Mastermind 33445 points

    Correct! We don't have a RTOS model. The embedded control can set the registers such as CC, CV and start charging. Please follow our user guide. 

    www.ti.com/.../BQ25710EVM-017

  • 0 in reply to Tiger Zhou
    Prodigy 35 points
    Thank you very much
    I will try to follow the user guide, modifying the registers from the mcu.
  • 0 in reply to Tiger Zhou
    Prodigy 35 points

    Another question, is it necessary to add a bms to the charger to control the charge and discharge?
    since in theory the charger could monitor the charging current and the system current through the 2 available shunt

    Summarizing, my system would have to be made up of 4 separate devices: 1 battery charger, 2 battery gauges, 3 battery protector (ov, oc, under voltage, temperature) and an mcu which interacts with the previous ones?

    Isn't there an integrated that has these 3 functions incorporated in a single integrated?

    Thanks in advance,

    Lucas

       
  • 0 in reply to Lucas Della Santina
    TI__Mastermind 33445 points

    Although the charger has a basic monitoring function, a dedicated  monitoring device can offer more resolution and the better accuracy. We don’t have a device with all-in-one ( charge, gauge and monitor) integrated functions.

  • 0 in reply to Tiger Zhou
    Prodigy 35 points

    Thanks so much

    I have a question about this parameter, is this used to protect the battery from under voltage? It seems a bit strange to me since through the internal diode of the Q5 mosfet there is no possibility of disconnecting the battery from the vsys

  • 0 in reply to Lucas Della Santina
    TI__Mastermind 33445 points

    That is right, we like the battery to supplement the system instantaneously. The PFET will further turn on to lower the impedance, in times of charging and discharging. Normally, the system rail is slightly higher than the battery voltage, thus PFET remains off. 

  • 0 in reply to Tiger Zhou
    Prodigy 35 points

    Thank you very much for your reply Tiger

    Of course, it is very necessary that the battery is connected to the system, to guarantee a constant energy supply to it (online system), but it would also be possible to use this same circuit with a brief modification (Q5 for the circuit that I've attached below), by adding one more mosfet, it would be possible to disconnect the battery in case of emergency (over-current or under-voltage, in discharge situation (regardless of the type of battery chemistry, it could be damaged)), since these parameters are already acquired through TP19 and TP20.

    This is just a suggestion to consider into future designs, it would be an extra feature for the same IC, at no additional cost. Also, it could be enabled from a register if needed.

    This is because the protection feature is only available for OTG mode, but not in "battery only discharge and converter off" mode (when all the current is flowing through VSYS).

    Thanks again 

    Lucas DS

  • 0 in reply to Lucas Della Santina
    TI__Mastermind 33445 points

    Thanks for sharing your thoughts. If you want to cut off the battery path completely, suggest implementing an AC switch which is controlled by external logic (not BATDRV). There is an issue in your proposal. In battery only conditions, there is no way to turn on since BATDRV needs battery available first.