TPS65988： VBUS no voltage.

Hello,

Could you elaborate the requirement? 

Thank You. 

Hi sir

I have a DOCK product.

The product is not connected to a power source, and the type_c interface is used to connect to a laptop,
I want no voltage on VBUS.Just plug in UFP, the system will not have power.

thanks

Hi sir

In addition，I set the role of PD to DFP, but VBUS still has voltage.

but the voltage will go from 0 to 5v and then from 5 to 0V and over and over again .

From the log, the laptop keeps sending source_cap to my product，

is this normal?

7002.log.rar

thanks;

Hello,

To get more background of your design, may I know why you do not want the dock to work in bus powered mode? You can configure PD controller to Source only mode to achieve this Or configure it as DRP and select PPx as wait for SRDY. 

For the second issue, could you share FW log and project file? 

Thanks

Prajith

Hi Prajith,

Below is the pjt file。

8372.CSB_DOCK_V8_TRY_DRP_external_path_20V2_5A_DiscIden_Dell_VID.rar

In order to achieve the effect I want, I changed the DRP of pjt to DFP, and then the following log appears

6724.7002.log.rar

thanks.

Hello,

This project file is not working on EVM. Do you have an EVM w/ you to test the project file you have? 

Otherwise, load a default template on your board and later add the custom functionalities. 

Thanks
Prajith

Hi Wei,

Could you tell me why you don't want VBUS? Or you just don't want power flow on VBUS? We can set 5V @0A PDO, in which 5V will asserts but no power will be sent out.

And if you want this port to support USB Flash, you should at least support 5V @0.9A.

In addition, please tell me the firmware version you use cause when I open your pjt file, no firmware is selected automatically.

Thanks

Bing

Hi Bing

Because our product is source only. We don't went VBUS when product don't plug in the power adapter(sink status).

It will cause issues. System will abnormal work when plug in UFP first and then plug in power adapter.

Hi Bing,

The firmware version we use is 6.1.1

thanks

Wei

Wei,

Let me clarify it.

The Type-C port on your dock will be only used as source mode, and if a power adapter is connected in the far end of the cable, abnormal phenomenon will appear. Now you want to disable VBUS to exclude the issue, is that right?

It should be noticed that, after plug in the cable plug, in no case VBUS would be disabled (except for fault condition) as the power communication is the first step of PD communication and all other subsequent PD message will be sent out based on this first step of power communication. Therefore, it means that your requirement cannot be met because it does not follow the Type-C Spec and PD Spec released by USB-IF.

And I think there are other ways to walk around the issue, but the first step is to clarify the issue and could you also share your test setup? You can upload a picture to depict it.

Thanks

Bing

Wei, the version number you attached is for GUI (the customization configuration tool), rather than firmware. The information for firmware version is highlighted in the red box as the attached image shows.

Thanks

Bing

Hi Bing

Since my computer is too caton on this forum, I hope I can contact you via email or WeChat,

email  : wei_liu@bizlinktech.com

phone ：13786084136

thanks

Wei

Hi Bing,

The Type-C port on your dock will be only used as source mode,The dock is not connected to a power source,the laptop should not power my docking station, which means there should be no voltage on VBUS. But our actual measurement found that the VBUS voltage will drop from 0 to 5v, then from 5 to 0V, and then change repeatedly.

I hope that when the dock is not connected to a power source, the laptop will not provide power to the dock. When connected to a power source, the docking station will power the laptop.

this is log PDlog_issue_1.zip

thanks

Wei