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two 18650 litium ion batteries cell

AIED BEBAR
Intellectual 680 points
Other Parts Discussed in Thread: BQ25616, BQ25611, BQ25883, BQ25886, BQ25887

hii 

i am looking for a charger ic that is capable of charging two lithium ion 18650 batteries in series in one configuration 7.4 volts

and two 18650 batteries in parallel 'it doesn't have to be the same chip. 3.7 volts

the charging will be done from a micro usb port 

the charge time must not exceed 2 hours .

and i be happy if there will be a typical application or schematics 

thanks 

  • 0
    TI__Mastermind 25800 points

    Hello,

    What is the input voltage? 

    And what is your max charging current?

    Regards,

    Joel H

  • 0
    TI__Guru**** 154276 points

    Hi AIED,

    What is the battery capacity?  What is the max output current of the usb port?

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Intellectual 680 points

    HII JEFF 

    hope you doing fine 

    we are talking about battery with a 2.5 ah capacity 

    and amax current of 1.5 amps from the usb port 

  • 0 in reply to AIED BEBAR
    TI__Guru**** 154276 points

    Hi AIED,

    For the 1S case and no host processor and normal power path (i.e. 5V to the system), I recommend BQ25616. If you have a host processor and want to develop some software, then BQ25611.

    For 2S case, you will need a boost charger so I recommend BQ25886 without a host processor and BQ25883 with a host processor.  If you want cell balancing, there is the BQ25887 which requires a host processor.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Intellectual 680 points

    hii jeff 

    i started a design with your recommendation  BQ25887 , and i saw the design EVM 

    I want the design to be set in hardware , i mean i don't want to wright any registers with my microcontroller and set the floating voltage or anything .

    i just want  a simple robust hardware design only to set the charging current to 1.5 A or 2 A  by a resistor and to plug the batteries and the charger automatically begins charging till it finish.

    i saw in the  BQ25887  data sheet an application design with 1.5A charging current ,if i build the design that is showed in the application design when i plug in the batteries the charging process wil start automatically, right ?

       

    and another thing can i use this charger to read the state of  charge of the batteries ?

      

  • 0 in reply to AIED BEBAR
    Intellectual 680 points

    hii jeff how are you doing 

    i have two more questions about the bq  BQ25887

    first i just want to clarify what i meant in the previous questions .  i want the charger to be  autonomous when i plug in the batteries, assuming they are good batteries i want the charger to start the charge cycle automatically ..

      .

    my new questions are :

    1) in my design i choose an equal value of the resistors 30k on the TS pin because i don't have a thermistor .did i choose right ?

    2) is the sns pins  num 15 and 16 are the pins  that goes to the load if i want to connect a load ?

    3 ) can i read the state of charge of the batteries ??

     

  • 0 in reply to AIED BEBAR
    TI__Guru**** 154276 points

    Hi AIED,

    Regarding 1, identical resistors for the divider is correct for disabling the TS function.

    Regarding 2, we disabled the SYS output so the SNS pins are not the same as SYS. We have not tested with a system load connected SNS.  You system load should be connected in parallel with the battery.  If you want the SYS output, I recommend changing to BQ25883 but you will lose the integrated cell balancing feature.

    Regarding 3, you can read the cell voltages using the integrated ADC.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Intellectual 680 points

    hii jeff ' how are you doing 

    thanks for your reply , 

    i saw in the data sheet that for 

    Autonomous Charging Cycle the CHRG_EN bit should be set how do i set this bit without host involvement or is it by default set yo 1 ?

    all i want is the charger to autonomously start the charging cycle with any host involmemnt by sending command on the I2C lines 

     

  • 0 in reply to AIED BEBAR
    TI__Guru**** 154276 points

    Hi Aied,

    Yes, charging is default enabled in I2C register. 

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Intellectual 680 points

    thanks jeff for your help