CX3 device detected only on one side of USB C

[jayesh_joshi]

I am running into strange issues where if I insert Type C USB3.0 on one side CX3-UVC camera is detected. But if a change in the orientation of the cable device is not detected. Please find below sch for reference. Also in older PCB with the same design, we are not facing issues. We have followed guidelines with each PCB. We are not sure what could be the reason.     

[Ajeethkumar_P]

Hi,

Type-C connectors have two rows with two USB 3.0 data lines(SSTX+-, SSRX+-). Based on the orientation of the Type-C connection, a Superspeed data mux has to select the appropriate SSTX+- and SSRX+-. From the above image, U7 will do this task in your design.

In your design, I could see that Rd(5.1k) is DNP. These resistors must be placed in your PCB to identify the orientation of Type-C. This could help resolve this issue.

Thanks,
Ajeeth

[jayesh_joshi]

@Ajeethkumar_P 

I was on leave for a few days. Today I tested with a 5.1K resistor but still ran into the same issue. 

[Ajeethkumar_P]

Hi Jayesh,

As the Mux has internal Rd pull down, external Rd is not needed.

Please share the USB PD Hardware analyzer logs(both pass and fail cases) so that we can check what would be the issue.

It is recommended to add USB OVP FET to avoid damage to the Mux and CX3 in case of an Overcurrent event. Please refer to this KBA to know about Type-C-based CX3 devices.

Thanks,
Ajeeth

[jayesh_joshi]

Hi @Ajeethkumar_P 

In our system, we do not have a power delivery IC as the system requirement is not more than 5V 3A.

We do not have a USB PD Hardware analyzer handy. Will windows event logs help with analyzing? 

[Ajeethkumar_P · Accepted solution]

Hi Jayesh,

As mentioned in this KBA, we recommend you add OVP FET which could save your IC in case of over voltage event during Connect or disconnect.

I suspect the issue should be with the Mux. You can replace the Mux and check.

Unless we have the Type-C hardware analyzer logs, it will be difficult to debug this issue further if the problem persists.

Thanks,
Ajeeth