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BQ25720: Impact on Removing BATFET on BQ25720

Widji Santoso
Prodigy 90 points
Part Number: BQ25720
Other Parts Discussed in Thread: BQ4050, BQ25731

Hi,

In our system, we plan to use BQ25720 as IC charger and BQ4050 as Battery gauge. If I take a look to BQ25720 typical application, there is a BATFET which in my understanding, it will act as ideal diode and precharge LDO.

But from the comparison table, I don't see BATFET power path and pre-charge LDO features on BQ25731. My question:

  1. Can we remove BATFET from the system? since I believe BQ4050 already have CHG and DSG FET. can the BATFET function replaced by those two FET?
  2. Do you have any concern / consequences in the future if BATFET is removed from the BQ25720 charging system?

This is topology diagram we will implement in our system

From this:

become this:

Thanks,

Widji

  • 0
    TI__Mastermind 33575 points

    Hi, Widji,

    Suggest BQ25731 for non-power-path battery charging application. BQ25731 has different settings. 

    One of the concern is to deal with dead battery situation. Do you have power to send out a command? BQ25731 employs a small charge current to charge up the dead battery. 

    Regards,

    Tiger

  • 0 in reply to Tiger Zhou
    Prodigy 90 points

    Hi Tiger,

    I was thinking if BQ4050 already have PCHG FET to charge small current during pre-charge. Could you explain more about non-power path battery charging application like when we should use this model instead of the other?  So it's not possible to remove the BATFET from BQ25720?

    Thanks,

    Widji

  • 0 in reply to Widji Santoso
    TI__Mastermind 33575 points

    The BATFET separates the battery from the system. If you don't need a separate system rail, you can use the non-power-path part such as BQ25731. The typical applications of BQ25731 are cordless power tool, battery pack and power bank. Due to the internal settings difference, not suggest BQ25720 for non-power path applications.