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Original question:

BQ25630: Choosing the right IC for LI ion battery charging

BQ25630: Choosing the right IC for LI ion battery charging

Avner Cohen
Intellectual 460 points
Part Number: BQ25630
Other Parts Discussed in Thread: BQ24800

Tool/software:

Hi,

Again, this post is not related to the BQ25630, but a general question – recommendation for IC charger controller for smart battery :

Well after the project had some variation the parameters for the IC were changed.

  • The battery we intend to use is by RRC and it is smart battery and Jeita compliant.
  • Communication of battery is  SMBus v1.1 compliant.
  • The battery Chemistry: Li-Ion, 2S2P configuration
  • It does not have TS thermistor pin, and the control is done by SMbus.
  • Therefore, the IC controller by TI must be Jeita compliant as well via SMbus. not using TS
  • The intention is to have a controller that is autonomous and does  not need host intervention. (level 2 charger)
  • The input voltage to the system is 12v so the controller does not have to be buck-boost , it can be Buck only.
  • The power of the load is max 12 W.
  • Equivalent IC by Analog devices company is the LT4100 which update the charging parameters following the battery advertisement of voltage/current adjusted to the change in temperature.

 

I am looking for Ti IC that is written to be Jeita compliant  for 2 cell battery that withstand all the parameters listed.

Help me to find the right one.

Thanks,

  Avner

  • 0
    TI__Mastermind 31370 points

    Hi Avner, 

    Thank you for reaching out via TI.com. Based on the requirements you list I suggest the BQ24800 charger IC. 

    Please let us know if you have any further questions. 

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    Intellectual 460 points

    Thanks Garrett for your quick answer.

     

    How did you choose BQ24800  please ?

    I ask this, since I have searched for Jeita compliant in the datasheet of the  BQ24800  but could not find any mentioning of it.

    Does the BQ24800 compliant with Jeita battery (Like the RRC company batteries) and can operate without host ?

    The RRC battery that we use RRC-2037 advertise the charging information to the controller and the controller should update the current/voltage of the charging automatically and autonomously .(Level 2?). Can you please confirm that the BQ24800 obey this action ? if yes, where in the database I can see evidence for this?

    If the answer is positive, please help me to learn on how the battery advertisement + IC update process is done (without TS pin involvement only via the SMbus) do you have some application note on this with the BQ24800 ?

    Thanks,

      Avner

  • 0 in reply to Avner Cohen
    TI__Intellectual 2010 points

    Hello Avner,

    BQ24800 is our best recommendation.

    We do not support JEITA without a TS pin on any of our chargers. We need the TS pin to accomplish JEITA or the battery gauge can read the battery temp and send a command to update the charger. 

    Regards,

    Charles Harthan

  • 0 in reply to Charles Harthan
    Intellectual 460 points

    Hi Charles,

    The LTC4100 by analog devices can fit the RRC battery we intend to use. The battery is being the Jeita compliant, and the IC controller implements level 2 autonomous operation without processor intervention on the charging and battery handling.

    Does Ti company have a similar IC charger controller which can replace LTC4100 for new project, So it doesn't have to be form-factor nor exact functional fit. But must be capable of working with SMbus and be autonomous without the need to check TS pin that my battery does not have?

     

    If there is no, please specify if Ti has a level 2 autonomous charger which is not dependent on TS pin and do comply with  (Rev. 1.1) SMBus. (Allows for operation with or without Host)

    Thanks,

      Avner

  • 0 in reply to Avner Cohen
    TI__Intellectual 2010 points

    Hi Avner,

    BQ24800 uses a simplified subset of commands from the Rev 1.1 SMBus standard.  BQ24800 does not have TS functionality and would rely on the battery gauge for that functionality.

    Can you please clarify what the requirements are for a level 2 autonomous charger?

    Regards,

    Charles Harthan

  • 0 in reply to Charles Harthan
    Intellectual 460 points

    Hi Charles,

    Please consider the attached block diagram.

    You can see that the charger IC is connected via the SMbus to the battery. The same SM bus is also connected to the Host. However, the Host has no function of handling the charging process. It just read the capacity cyclically informing the user the current state of battery capacity , or initial setup at power up. It does not read the messages of the battery and adjust the current/ voltage. Thus the circuit is Implementing level 2 charger without the host handling the charging process.

    JEITA controlling is done by the battery, not by the CPU nor by the charger IC. The RRC battery we intend to use, the Jeita process controlling is done automatically by the battery.

    In the datasheet of the RRC battery we intend to use written:

    “Only a “Smart Battery Charger” (compliant to the [SBCS]) is suitable to charge this RRC smart battery.

    The battery requests different charge voltages and charge currents over temperature and also over lifetime. It is necessary that the charger is able to communicate with the battery and react to the battery requested charge parameters.”

    As I understand the LTC4100 comply to this. But I am looking for more advanced IC with preferably with buck +boost.

    Thanks,

    Avner