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TPS25751: TPS25751+EEPROM+BQ25798

Mulin Chou
Prodigy 175 points
Part Number: TPS25751
Other Parts Discussed in Thread: BQ25798, , TPS2121

Tool/software:

Hi,

My Battery is 3S1P LiFePO4.

I will use EEPROM to control TPS25751 & BQ25798 function.
What do you suggest Type-C to VAC1 or VAC2.
If PV=VAC1, Typc=VAC2, when PV was not supply change to type-c to supply VBUS.
My question, the type-c always in existence, it not turn to PV forever, until the type-c is unplugged change to PV supply, right?

tks.
Mulin

  • 0
    TI__Mastermind 34466 points

    Hi Mulin, 

    Looking into this and will provide update early next week! 

    Thanks and Regards,
    Raymond Lin

  • 0
    TI__Mastermind 34466 points

    Hi Mulin, 

    It should be fine to use either VAC1 or VAC2 of BQ25798 to be connected to TPS25751 PPHV. From a TPS25751 (PD) perspective it does not matter. There are additional settings on BQ25798 to be able to select between which path (USB-C or PV) to draw power from. I'll forward this thread to the BQ team for further inputs on BQ25798. 

    Please let us know if you have any further questions or concerns on TPS25751! 

    Thanks and Regards,

    Raymond Lin

  • 0 in reply to Raymond Lin
    Prodigy 175 points

    thank you Raymond,

    So will the BQ team reply to me here in the future?

    Or I will need ask a new question for BQ25798?

    Mulin

  • 0 in reply to Mulin Chou
    TI__Guru**** 166626 points

    HI Mulin,

    The BQ25798 auto selects VAC1 by default but auto switches to VAC2 if it is present when VAC1 drops below UVLO.  There are I2C register bits to force change from VAC1 to VAC2 and vice versa.  By default, VAC1 runs USB BC1.2 current output detection over the D+/D- lines but VAC2 does not.  There is a bit to disable this detection.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 175 points

    Hi,

    I use TI EEPROM+TPS25751+BQ25798 GUI solution, so I need know what are the limitations of HW application?

    My question,

    What do you suggest Type-C to VAC1 or VAC2.
    If PV=VAC1, Typc=VAC2, when PV was not supply change to type-c to supply VBUS.
     the type-c always in existence, it not turn to PV forever, until the type-c is unplugged change to PV supply, right?

    I need to know that if the HW application can not support it, I have change EEPROM to MCU.

  • +1 in reply to Mulin Chou
    TI__Guru**** 166626 points

    Hi Mulin,

    You will need an MCU and software to force a change from always present VAC2 to not always present VAC1.

    Regards,

    Jeff

  • +1 in reply to Jeff F
    TI__Guru**** 166626 points

    Hi Mulin,

    Alternatively, you could add a TPS2121 MUX chip instead of using BQ25798's integrated MUX and external FETs.  This chip has a pin for selecting the preferred input when present.

    Regards,

    Jeff