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TPS65981: enabling VBUS power

Wim2532
Intellectual 330 points
Part Number: TPS65981


Dear,

I have a question about the TPS65981 USB PD controller.

For a project I need an enable pin for this controller, in such way, that VBUS power only is enabled when the host controller asserts its power available pin.

I use the program TPS65981_2_6_7_8 Application Customization 4_03 to generate customized firmware for the TPS65981.

But when looking at the IO pin options, I cannot find a specific enable pin to override the TPS while keeping it functional.

Is there a way to set this up ?

 

The problem is that the USB 3.0 driver stack can get confused between power states when the VBUS remains present while the driver software expects VBUS to be off.

Is there a reference hardware design example how to proceed ?

Thank you very much in advance.

 

With kind regards,

 

Wim van der Steeg

AVS Netherlands

  • 0
    TI__Mastermind 36756 points

    Hi Wim,

    The TPS65981 does not have an enable pin that could be used for this application. However, from what it sounds like, you do not want the TPS65981 to provide VBUS unless a certain condition is met in your system. Since you do have a host controller in your system, I would instead suggest modifying the "Externally Powered" bit in the Control Configuration register (0x29). If the externally powered bit is not set, then the TPS65981 would never be able to source VBUS. Setting the Externally Powered bit would allow the TPS65981 to become a Source. You can modify this bit by writing to the 0x29 register of the TPS65981 over I2C. 

    Thank you,
    Eric