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BQ25713: BQ25713 as LIFEPO4 backup manager

Francisco González
Prodigy 150 points
Part Number: BQ25713
Other Parts Discussed in Thread: BQ24715, BQ24780S,

Hi,

I'm designing a backup system with LIFEPO4 cells (3.2v nominal, 3.5Vmax, 2.8Vmin), 12V Vin and 12Vout.

1. Can I charge the battery to 14V (4s) and have simultaneusly 12V on VSYS?

2. When I remove Vin, Can I have 12V on VSYS regulated from the 14V to 11.2V from VBATT?

3. Are this transitions performed automatically?

4. What about using a 2S or 3S configuration?

5. What about bq24715 or bq24780S for this job?

Regards,

Fran

  • 0
    TI__Expert 3320 points

    Hi there,

         Thanks for asking.

    1. Can I charge the battery to 14V (4s) and have simultaneusly 12V on VSYS?

         Yes, you can set charge voltage to 14V in REG0x05/04h() .

          When battery is depleted(Lower than 12V).VSYS could be 12V if you set VSYSMIN(REG0x0D/0Ch) to 12V.

          When battery is increased higher than 12V, then SYS votlage will follow VBAT rise up.

    2. When I remove Vin, Can I have 12V on VSYS regulated from the 14V to 11.2V from VBATT?

          Nope, When Vin is removed then VSYS voltage will only be provided by VBAT through BATFET and distribution trace, therefore it can not be higher than battery voltage anymore.

    3. Are this transitions performed automatically?

         Before Vin removal, if VSYS is regulated higher than VBAT, then after Vin is removed, VSYS will automatically reduce to VBAT.

    4. What about using a 2S or 3S configuration?

        For 12V VBAT, 2s configuration can't be used, because SYSOVP under 2s is 12V which is too close to normal operation state. 3s should be good to go.

    5. What about bq24715 or bq24780S for this job?

        For your buck boost application, BQ25713 fits better for your application.  bq24715 or bq24780S are all buck chargers.

    Regards