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bq24210 and lm2621 DC-DC converter to charge Li-Ion battery

Rudy Zhang
Prodigy 40 points
Other Parts Discussed in Thread: BQ24210, LM2621, BQ24650

hi, i am planning to charge 3 to 4 Li-Ion batteries rated at 2000mAh, 3.7V each. I already have one bq24210_Li-Ion Battery Solar charger evaluation board and one lm2621_DC-DC converter evaluation board. 

my question is, can i connect the batteries in parallel and let the bq24210 evaluation board to charge them? or i need to get the bq24210 chip?? 

The lm2621_DC-DC converter evaluation board is for the batteries output, because i need to have 3V, 5V, and 9V outputs. i guess i need to have 2 of this converter, one for 5V, another one for 9V right??

Thanks

  • 0
    TI__Guru**** 167196 points

    The bq24210EVM will charge the batteries in parallel but very slowly.  The bq24210 provides 800mA max charge current and you will have 4 x 2000mAhr = 8000mAHr equivalent battery to charge which will take at least 8000mAHr/800mA = 10 Hrs.  Perhaps you should consider moving to a higher power solar charger like bq24650 if your solar panel has an MPP > 5V.

    The LM2621 is a step or boost converter only so you will need two in order to provide 9V and 5V.  If you need a regulated 3V, you will also need a separate step down or buck converter.

  • 0 in reply to Jeff F
    Prodigy 40 points

    Thanks Jeff. 

    I am wondering how do i adjust the output voltage of the LM2621 evaluation board? I have one evaluation board but i dont see any pin there for me to change output voltage. 

    what is the difference between the bq24210EVM an dbq24210 chip? 

    Thanks

  • 0 in reply to Rudy Zhang
    TI__Guru**** 167196 points

    I will forward this post to the proper forum for the LM2621 as I do not directly support this product.  If it is similar to other evaluation boards (i.e., EVMs), you may have to change a feedback resistor to change the output voltage.


    Regarding the bq24210EVM vs. bq24210, the EVM (evaluation board) has the bq24210 chip on it as well as the other supporting passives in order to allow you to evaluate the IC.