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BQ25713: For Single Cell battery charger + 8A load current

Dhvanish Parekh67
Prodigy 205 points
Part Number: BQ25713

Hi,

I have designed a battery charging circuit around BQ25713 considering following power requirement

Output power (load): 4.2V, 8A

A battery specification: 1S8P (20AH @ 4.2V nominal voltage).

Charging current: 1A (when charging the battery load will take 6.5-7A current.)

While designing I have took reference from EVK SLUUBT8A.pdf document. Please find attached PDF.

I have a queries as below:

1) ILIM_HIZ pin: As per equation I have calculated voltage for the pin and it is coming 4.2V (1 + 40 x 8 x 0.01 ). Pl verify the value of R666 & R667.

2) Is it required to put input protection circuit containing Q73 and Q74? What impact it will have if I directly provide source supply to IC?

3) In my design I do not have USB charging application, so it is not required to provide power in the reverese direction to VBUS. While on backup battery will constantly give supply to VSYS_4V2 rail only.

Also, please do overall review and provide your comments if anything missing.

Battery Management-sch.pdf

  • 0
    TI__Genius 16175 points

    Hi,

    Below list is my suggestion. Thanks

    Q1: Could you advise what is your input current limit specification? is it really 8A? If you program ILIM_HIZ pin voltage above 4V, this Ilim function will disable.

    Q2: You don't need Q73/74 is circuit design. But please add 4pcs 10uF cap in SYS_IN for bulk cap purpose.

    Q3: I don't quiet understand your question, could you explain more detail? Or do you mean you don't want OTG feature? If yes, then there is no different H/W circuit design.

    Thanks

  • 0 in reply to Paul Yeh
    Prodigy 205 points
    Hi Paul,

    Many thanks for quick response!


    Q1: Could you advise what is your input current limit specification? is it really 8A? If you program ILIM_HIZ pin voltage above 4V, this Ilim function will disable.
    [Dhvanish]: Yes it is. Power requirement in my design: O/P: 4.2V @8A. and for that giving 5V as input voltage so approx input current required will be 7.5-8A. PL advise how I can satisfy this requirement.

    Q2: You don't need Q73/74 is circuit design. But please add 4pcs 10uF cap in SYS_IN for bulk cap purpose.
    [Dhvanish]: Noted

    Q3: I don't quiet understand your question, could you explain more detail? Or do you mean you don't want OTG feature? If yes, then there is no different H/W circuit design
    [Dhvanish] Yes correct, not using USB or OTG function. Noted.

    Thanks,
    Dhvanish Parekh
  • 0 in reply to Dhvanish Parekh67
    Prodigy 205 points
    I am looking answer for query on 8A load current capacity.
  • 0 in reply to Dhvanish Parekh67
    TI__Genius 16175 points

    Dhvanish,

    For BQ25713 application, the max input current should be 6.35A at 10mohm input sense resistor. And in theoretically, if you reduce 10mohm to 8mohm then your input current limit can be up to 7.9A around. So it can support 4.2V/8A loading. But due to we only finish 10mohm sense resistor validation. So you can try in your system and verify it.

    And you should disable ILIM_HIZ pin function, please program 0x32[7]=0 to disable external pin setting.

    Thanks