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USB-PD-CHG-EVM-01: 5V OTG / Power Delivery Source

Achim Beyer
Prodigy 40 points
Part Number: USB-PD-CHG-EVM-01
Other Parts Discussed in Thread: TPS54531, BQ25792, TPS25750,

Hi,
when reading the design guide, I found various references to the 5V source in OTG / PD mode.

For the buck converter TPS54531 it is described that this serves as 5V source and only the higher voltages come via PPHV from the charger BQ25792. (Only?) for a Sink-Only application, this device is not needed.

On Figure 3-1 "TPS25750 Application Selection" I cannot find a selection for different sources via PP5V and PPHV.
On Figure 3-9 "Sourcing 5 V with BQ25792 in OTG Mode" and following text it is described that the BQ25792 generates the 5V.

How does the USB-PD-CHG-EVM-01 really work in standard configuration?
How can I configure different sources using the Application Customization Tool? 5V via PP5V and higher voltages via PPHV


As far as I understand, the 5V converter TPS54531 is only needed for higher output currents >3A. Up to 3A, the BQ25792 can also be used as 5V source. This should be the "BQ only selection" in the Application Customization Tool. Is that true?

Regards,
Achim

  • +1
    TI__Mastermind 40845 points

    Dear Achim,

    The 5 V sourcing is entirely provided by the buck converter. Please see "TPS54531 Buck Converter" in the design guide.

    "For Sourcing capabilities, this design uses the PP5V power path to supply a 5 V source and the PPHV power path to source higher voltages. Therefore to keep a constant 5 V system source readily available on VBUS for the PD controller and for VCONN support, a buck converter is needed. For this design, the TPS54531 provided a good solution, it features integrated FETs and a wide input voltage range. Since this converter will be connected to the System rail of the battery charger, it can handle any input voltage in the range of 3.5 V to 28 V and provide a 5 V output capable of delivering up to 5 A. For a Sink-Only application, this device is not needed and a 5 V rail can be omitted."

    The 5 V sourcing is guaranteed by the buck converter. In order to configure higher source voltages select higher source powers in question 2 as shown in Figure 3-2 of the design guide.

    Thanks,

    Mike Emanuel

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