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TPS65981: Operate of the TPS65981 in Sink mode without VIN_3V3

Dimitri Schmidt
Prodigy 70 points
Part Number: TPS65981
Other Parts Discussed in Thread: TPS65982, , TPS65982-EVM

Hi Ti Team,

I have a question to the dead battery mode of the TPS65981.

As I read in the datasheet, it is possbile to operate the device with VBUS only, without 3.3V on VIN_3V3. The TPS65981 then goes into dead battery mode. By selecting the right voltage on BUSPOWERZ I can choose the external power path to sink to my further system. My application is only in sink-mode, so I think the TPS65981 can stay in dead battery operation or is there any problem?

Thanks for your help.

Regards

Dimitri Schmidt

  • 0
    TI__Mastermind 36751 points
    Hi Dimitri,

    If your design is a sink only, there is no problem operating solely in dead battery mode. If you ever wanted to switch to a PD source, you would have to clear the dead battery flag before doing so.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Prodigy 70 points
    Hi Eric,

    I have another question to the TPS65982. Is it possible to get the information from the PD-Controller, which current is negotiated? I have no MCU in my project, the PD-Controller should work in stand alone.

    Thanks for your help.
    Dimitri
  • 0 in reply to Dimitri Schmidt
    TI__Mastermind 36751 points
    Hi Dimitri,

    The TPS65982 can operate in stand alone. However, if you want to read back what the actual negotiated current is, an I2C master is required. You could test this using the TPS65981EVM and the TPS6598x application customization tool. There is a feature called "debug mode" in the tool that allows you to read back the Host Interface registers during run time using the included FTDI programmer board.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Prodigy 70 points
    Hi Eric,

    thanks for your answer. I already have the TPS65982EVM and try to debug the board with the C232HM FTDI Adapter. Unfortunately I get an error message in the Application customization tool:

    Exception Encountered during I2C Test Read:*** ERROR in FTDI call (I2C_OpenChannel), status: 1
    <type 'exceptions.Exception'>

    I think the required drivers are installed. Do you have an idea what is the problem?

    Tanks for your help.
    Dimitri
  • 0 in reply to Dimitri Schmidt
    TI__Mastermind 36751 points
    Hi Dimitri,

    Certain users have had issues with the FTDI drivers on their PC's. Can you refer to the following thread and let me know if it resolves your issue?
    e2e.ti.com/.../2231898

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Prodigy 70 points
    Hi Eric,

    yes this thread I already read. I tried several drivers, but nothing from them works. I also have another error message than the users in this thread. I also think my adapter is detected by the configuration tool. But I get this error in FTDI call.

    Tanks for your help.
    Dimitri
  • 0 in reply to Dimitri Schmidt
    TI__Mastermind 36751 points

    Hi Dimitri,

    Can you confirm the switches on your FTDI board?

    Thank you,

    Eric

  • 0 in reply to Eric Beljaars
    Prodigy 70 points

    Hi Eric,

    I don't have such FTDI board. I only have the TPS65982-EVM and a FTDI Adapter (C232HM-DDHSL-0), like shown in the picture below. Do I need a FTDI board or another Tool?

    Thanks for your help.

    Dimitri

  • 0 in reply to Dimitri Schmidt
    TI__Mastermind 36751 points
    Hi Dimitri,

    I have not tested with that FTDI. I am not sure if it would work with the TPS65982. You could order the TPS65981-EVM that includes the FTDI board that I pictured.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Prodigy 70 points
    Hi Eric,

    in the User Guide of the TPS65982-EVM is the Aardvark SPI programmer mentioned for firmware installation. Do your think this tool would better work with my board for debugging and programming with the the application customization tool?

    Than I have a further question to the dead battery mode. I tested the EVM by only supplying with VBUS, without any 3V3 supply. The controller works than in dead battery mode and negotiate only PDO1 with vsafe5V. The controller drives the mosfets and I can measure the 5V. Now is my question if the controller also can negotiate another PDO, with 20V for example? Moreover I have no MCU in my application, so the dead battery flag can not be cleared.

    Thanks for your help.

    Dimitri
  • 0 in reply to Dimitri Schmidt
    TI__Mastermind 36751 points
    Hi Dimitri,

    You could also use an Aardvark if you have one available. Just make sure you install the Aardvark drivers as explained in the Application Customization Tool's User Guide.
    You could also sync 20V in dead battery mode operation, you would just need to configure the device to do so. Our Host_DRP template in the configuration tool contains a 20V dead battery mode configuration.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Prodigy 70 points
    Hi Eric,

    thanks for your reply.
    Which setting did you mean to sync 20V in dead battery mode?

    Thanks for your help.
    Dimitri
  • 0 in reply to Dimitri Schmidt
    TI__Mastermind 36751 points

    Hi Dimitri,

    The following template will allow you to sink 20V in dead battery mode:

    Once you open this template, you can program it onto your TPS65981EVM by clicking device --> Flash App Firmware to Device. You can then power cycle the device and sink 20V in dead battery.

    Thank you,

    Eric