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TPS25751: TPS25751 PPS

Camron Vossberg
Prodigy 15 points
Part Number: TPS25751
Other Parts Discussed in Thread: LM5148, BQ25792, BQ25756

Tool/software:

We are developing a USB-C device that can act as a source to provide 5-20V at up to 65W. We have a separate DC supply voltage that powers our device and can be bucked down to the PD-negotiated voltage (using something like a LM5148). We have a microcontroller in the device, so we can control the TPS25751 and buck regulator as necessary. There is no battery in the product. We have a couple questions:

- Do we need a EEPROM to store the configuration, or can we program everything with the MCU via I2C?

- The TPS25751 is designed around communicating with a BQ25792 or BQ25756 battery charger buck-boost chip. Can we use our MCU to control the buck instead, and how would we synchronize the PD contract voltage (when the sink requests a profile, how does the MCU know to adjust the buck voltage)?

- We want to be able to plug a laptop into the USB-C connector and communicate via USB with the MCU so we can update firmware. We will sometimes need to do this while the device has no power on its own. Is there any issue in getting power from the laptop while we do the firmware update? If our device's input power is then connected to our device while it is in this condition, can we switch to providing power to the laptop?

Thank you for your help!

  • 0
    TI__Mastermind 33946 points

    Hi Camron, 

    TI US is out for Labor Day, please expect delays in response until 09/02. 

    Thanks and Regards,

    Raymond Lin

  • 0
    TI__Guru 62891 points

    Hello,

    Camron Vossberg said:
    - Do we need a EEPROM to store the configuration, or can we program everything with the MCU via I2C?

    You can program the PD controller from the MCU via I2C.  https://www.ti.com/lit/pdf/slvafv8

    Camron Vossberg said:
    - The TPS25751 is designed around communicating with a BQ25792 or BQ25756 battery charger buck-boost chip. Can we use our MCU to control the buck instead, and how would we synchronize the PD contract voltage (when the sink requests a profile, how does the MCU know to adjust the buck voltage)?

    The solution was designed to work with the BQ devices listed in the GUI tool.  As an alternative you can try to utilize the interrupt associated with a new RDO (13) and then read the register 0x35 to see what contract was negotiated. https://www.ti.com/lit/ug/slvucr8a/slvucr8a.pdf  .  Please be aware of the timing and the requirements for providing the output voltage relative to PS_RDY.

    Camron Vossberg said:
    - We want to be able to plug a laptop into the USB-C connector and communicate via USB with the MCU so we can update firmware. We will sometimes need to do this while the device has no power on its own. Is there any issue in getting power from the laptop while we do the firmware update? If our device's input power is then connected to our device while it is in this condition, can we switch to providing power to the laptop?

    The TPS2571 supports dual role power.  In the event that the device is not powered the dead battery feature will automatically sink the implicit 5V contract.  Configure the dead battery settings (ADCINx) for your application.  You can design your system to perform a power role swap once the input power is connected.

    Regards,

    Chris