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Original question:

TPS25730: TPS25730

TPS25730: Can someone explain the "TPS25730 Technical Reference Manual" ?

Sila ozer
Prodigy 40 points
Part Number: TPS25730

Tool/software:

Hi All,

We are using the mentioned part above. We have done the pin strapping. We also want to monitor the device with I2C. 

I still don't understand how to use this part. If I connect to a power source, would the power negotiation be automatic?

Do i have to initiate with a i2c command?

How do I check if the power negotiation was successful? ALSO, what does RX_SINK_CAPS Register and TX_SINK_CAPS registers mean and used for?

What are the other registers mean and used for ?

What are the differences between pdos?

How do i put the device to the sleep mode?

Do i have to do the pin strapping AND write to TX_SINK_CAPS?  

I wish there were more explanation to these terms. I am a beginner in usb c controls, and i find it quite sad that, this part is just left out with no example code or app notes 

  • 0
    TI__Mastermind 37855 points

    Hi Sila,

    Please give us a couple days to respond to your questions.

    Thanks and Regards,

    Chris

  • 0 in reply to Christopher Lim1
    TI__Mastermind 37855 points

    HI Sila,

    Sila ozer said:
    I still don't understand how to use this part. If I connect to a power source, would the power negotiation be automatic?
    Sila ozer said:
    Do i have to initiate with a i2c command?

    Screenshot from the TPS25730EVM user guide

    Yes, on power up, the TPS25730 obtains configuration from the ADCINx pins. When a USB-C PD source is connected to the Type-C port, the power negotiation will happen automatically. No I2C command is used.

    Sila ozer said:
    How do I check if the power negotiation was successful?

    There is a plug event GPIO that indicates a device has connected to the type-C port.

    Sila ozer said:
    ALSO, what does RX_SINK_CAPS Register and TX_SINK_CAPS registers mean and used for?
    Sila ozer said:
    What are the other registers mean and used for ?

    RX_SINK_CAPS

    - If a Source sends a sink caps, the pts25730 will store the Received sink caps here.

    TX_SINK_CAPS

    - Store the TPS25730's sink capabilities. A list of SInk PDOs that is generated from the ADCINx upon boot. If a source requests sink caps, these are the Transmitted sink caps

    ACTIVE_CONTRACT_PDO

    - In step 3 of the EVM user guide image above, a source will send a "Source Capabilities" message, which is a list of the PDOs it supports. When the TPS25730 selects one, the Source PDO is stored here

    ACTIVE_CONTRACT_RDO

    - In step 4, the TPS25730 requests one of the PDOs. The TPS25730 request contains additional information, the request data object that is sent is stored here. One significant difference is the current. The Source active contract PDO may offer more power (current) than the sink needs. The sink may request a specific PDO, but request less current than the source offers.

    To check the active contract, you need to check both the Active PDO and RDO to know what voltage and current have been negotiatied.

    The format for the PDO and RDO can be found in the USB-PD spec that is found on the USB-IF website.

    Sila ozer said:
    What are the differences between pdos?

    I'm not entirely sure what you are asking here. A PDO is a power data object, which describes a possible PD contract that can be negotiated. Typically it provides information on contract type, voltage, and max current. All can vary.

    Sila ozer said:
    How do i put the device to the sleep mode?

    Sleep mode is automatically entered after ~100ms of CC detached and no activity. There is no way to force the device into sleep mode.

    Sila ozer said:
    Do i have to do the pin strapping AND write to TX_SINK_CAPS?  

    No, just the pin strapping.

    Thanks and Regards,

    Chris