• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Subscribers 64 subscribers
  • Views 580 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

bq24610 EVM charge current

Ronald Deang
Intellectual 260 points
Other Parts Discussed in Thread: BQ24610

Hi, I'm working with a bq24610 EVM. In the user guide it lists the battery charge current as 2 A min, 3 A typical, and 8 A max. The cells I am using have a recommended charge rate of 900 mA and a max charge rate of 1.8 A.

Can I go below the 2 A minimum charge rate? According to the bq24610 manual, ICHARGE = VISET1 / (20 x RSR). So for a 900 mA charge rate, I would set VISET1 to .18 V? Will this work?

Thanks,

Ron

  • 0
    TI__Guru**** 165786 points

    You change the resistor Rsr in order to set the charging current.  For your application, you want 0.9A=2V/(20*Rsr) so Rsr = 0.11ohm.

  • 0 in reply to Jeff F
    TI__Guru 56650 points

    bq246xx has a cycle by cycle current limit. When change sense resistor to higher value, please also calculate the ripple current to make sure the peak current lower than cycle by cycle current limit. 

    There is a calculation tool is available in http://www.ti.com/litv/zip/sluc175d

  • 0 in reply to Wang5577
    Intellectual 260 points

    Awesome, thanks guys. But I'm still a bit confused; if you're supposed to replace RSR, what is jack J3-ISET1 for? I thought you can provide a VISET1 anywhere between 0 V and 2 V.

  • 0 in reply to Ronald Deang
    TI__Guru 56650 points

    I

    CHARGE = VISET1 / (20x RSR)

    So, Rsr value and Viset1 value both can change the charging current.  You can decide Rsr and Viset1 value basing on the power loss of Rsr; ISET1 accuarcy; the inductor ripple current...

  • 0 in reply to Ronald Deang
    TI__Guru**** 165786 points

    Correct.  On the EVM, VISET is provided by a voltage divider off of VPULLUP=VREF=3.3V.  The voltage divider drops ISET1 down to 0.6V so, Rsr=R18=0.01ohm, the EVM is set for 3A charging.  If you want to change the charge current, you can either change VISET or change the sense resistor R18.  By lowering the VISET voltage, you can lower the sense resistance size and not waste power across a larger resistor for smaller charging currents.   If that is not a concern to you then simply change R18 on the EVM to 0.33ohm or change VISET to 0.18V, as you previously suggested.  To change VISET, you could change the voltage divider R11 and R12 or move jumper JP3 to VEXT and connect a the appropriate voltage (relative to the resistor divider) to J2 VEXT connector or simply connect that external voltage directly to J3.  Please ensure that VISET does not exceed 2V.