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Required a battery charger IC

Namitha K M
Prodigy 200 points
Other Parts Discussed in Thread: BQ2000, BQ24610

Hi,

I want an IC suggest for the charging section of my power board. The requirements for my board are as follows,

  • Input is 36V DC.
  • The battery voltage is 25.9V (no. of cells in not considered as of now). It would be better if there is a wide range to supply the number of cells. May be around 3.7V per cell, for this 25.9V may be 7 cells will come.
  • I2C interface from the controller.

We can step down the input voltage, if required, but it has to support the battery voltage.

Can you guys suggest the suitable charger IC or if you can share any design, schematic, would be usefull.

Thank you,

  • 0
    TI__Guru**** 165886 points

    Hi Namitha,

    TI currently does not have single IC solution for charging from 36V input up to 26V.  The BQ2000 family of charge controllers could be used for this application but it would require a step down regulator/converter to provide its 5V, as well as external FETs and diodes and an inverting gate driver.  There may be a better multi-chip solution at https://www.ti.com/reference-designs.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 200 points

    Hi Jeff,

    The link you shared is showing some error to open, kindly help with this.

    From 5V input, the BQ2000 is capable of charging 25.9V battery.

    Thank you, 

  • 0 in reply to Namitha K M
    TI__Guru**** 165886 points

    Hi Namitha,

    The more generic link is .

    The BQ2000 IC controller needs a 5V input rail but the buck converter that the BQ2000 drives needs higher than 25.9V to charge the cells.  To get the 5V power rail for the BQ2000, I suggest adding a linear regulator or dc/dc converter that steps down the input power rail to 5V.  Also, I suggest adding an inverting gate driver to drive the high side power FET.

    Regards,

    Jeff 

  • 0 in reply to Jeff F
    Prodigy 200 points

    Hi Jeff,

    The IC BQ2000 will support upto 4 cells battery right but my application may include upto 7 cells. Also from this IC 5V input can it will be sufficient to charge the 25.9v battery, each cell is 3.7v.

    Thanks

  • 0 in reply to Namitha K M
    Prodigy 200 points

    I think i am missing out some calculation wrt charging circuit, can you just suggest which all the parameters i need to look into for charging my 25.9v,4000mAH battery with 36v input, like the voltage and current required to charge that battery, if i am stepping down the input voltage, 36v, at which voltage level i need to step down...will charging circuit works differently compared to direct charging of battery which is done by giving required input voltage.

  • 0 in reply to Namitha K M
    TI__Guru**** 165886 points

    Hi Namitha,

    The BQ2000 is buck controller so you will need an input power that is at least 0.5V higher than the your maximum cells.  The BQ2000 IC itself can only take 5V input so you would need to add a 5V linear regulator or dc/dc converter to power the BQ2000 IC itself.  The BQ2000 high side PFET gate driver will also need a level shift.  I tried to find a gate driver that would work but could not, so you would have to build one using discrete components, similar to what is on the EVM.  However, at such high power (4A) the low side buck converter diode will likely be too inefficient.  There are low side gate drivers to drive FET instead of diode, that might work, but at this point the design is getting too complicated (LDO for 5V, level shift for high side driver, low side driver).  I think the best solution TI can offer would be for you to use a LiIon charger like BQ24610 with max input voltage 28V and termination disabled and then add the BQ2000 without the buck converter components (or a microcontroller with ADC) to monitor charge voltage and tell the BQ24610 to stop charging.  The BQ2000 has output voltages that report when -dV/dt and dT/dt has occurred for termination.

    Regards,

    Jeff