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BQ25792: Need help with BQ25792 (Battery Charger IC) + TPS25750D (USB PD 3.0)

Part Number: BQ25792
Other Parts Discussed in Thread: TPS25750

Hello,

I have a couple of question regarding BQ25792 (Battery Charger IC) and TPS25750D (USB PD Interface):

  1. When using TPS25750D + BQ25792 as in the reference design below, if the Type C connector from the circuit is connected to a wall charger that supports USB PD 3.0 and advertises it's source capabilities, how can we select the one we would like to use from the options using TPS25750D through a Host Controller? 
    1. https://www.ti.com/lit/ug/tiduey1/tiduey1.pdf?ts=1627413611537&ref_url=https%253A%252F%252Fwww.ti.com%252Ftool%252FUSB-PD-CHG-EVM-01 
  2. Now when the same circuit is connected as a Source to a cell phone, say Samsung S21, how does TPS25750D advertise the options for the circuits source capability. Is there a way to set it through I2C?

  3. Can TPS25750D recognize charging protocols such as Quick Charge 4.0/5.0, Samsung Super fast Charging 1.0, and so on, when connected to a wall adapter?

  4. In the reference design above (image shown below), why is a separate 5V DC/DC used for sourcing. Couldn't we just use the VBUS net (with BQ25792 in reverse mode) with a switch to direct it to the output?

  5. When using 2S cell configuration with BQ25792, can you recommend some cell balancing IC?

  • One more question, if we don't need Power role swap and Data role swap for our design, do we really need TPS25750D?

    Can BQ25792 do all USB PD 3.0 negotiations when Sourcing or Sinking? Sourcing or Sinking mode will be set by host controller, and each will have it's own Type C connector, and Power path will be directed by a switch.

  • Could you please help us here?

  • Izzy,

    Here are answers to you questions

    1.  The TPS25750 Configuration GUI will allow you to configure the TPS25750 and the TPS25750 Host Interface Technical Reference Manual describes how to update the PDO.  The part is intended to act as a very autonomous interface where you configure the PDO (Voltage and Current) that you wish to support and it will select the highest power option from the DFP (Charger) that you connect

    2.  The configurations are stored on the EEPROM or loaded through our CPU as long as you have 11KBYTES of extra flash to store the patch and configuration information.  

    3.  QC4/5 and Samsun Super fash Charging 1.0 is not supported

    4.  This does not work.  The part requires that the 5V rail be present and be powered by a buck converter with ~4A of source current capability.

    5.  I am not knowledgeable enough to address any cell balancing options