TUSB1002A: Schematic review for SuperSpeed RX/TX

Hi,

Is J2 the USB-A connector or is this a board to board connector? If it is a USB-A connector that is exposed to the customer, I recommend adding ESD diodes to the Superspeed SSTX/RX lines between the TUSB1002A and J2.

Can you show a block diagram of the system? I'm not sure which side connects to the USB host/device and which side is routed to the USB connector.

For a description on EQ, VoD, and DC gain, please see this E2E thread.

Best,

Shane

Hi Shane,

Thanks a lot for your reply. The TUSB1002A is used in the middle of data lines as a signal relay.

We will follow you suggestion to add ESD diodes to the Superspeed SSTX/RX lines between the TUSB1002A and J2.

Best Regards,

Hi Shane,

Thanks a lot for your suggestion, and we have redesigned the schematic and made samples for testing.

TUSB1002A SCH.pdf

Now we faced a new problem, that is, when we use this USB cable to connecting a camera , if we unplug J1 (device end), and the J2 connect to the computer normally, the USB device icon of the PC device manager will not disappear. And the device manager list will update only by reinserting J1 to the USB port.

Is there any suggestion for this issue?

Thanks,

Kind Regards

Hi,

1. Does unplugging J2 remove the device from device manager?

2. How is the type-C port implemented on J1? Typically you will need a CC controller and MUX to convert Type-C to Type-A.

3. Does the 'scan for hardware changes' button remove the device correctly?

Best,

Shane

Hi Shane,

Thanks for your suggestion, we solved this problem by floating the mode pin.

Now we have faced another quesiton, that is, when we connected our equipment and computer, the power was supplied by the VBUS of computer and then power to the equipment. There will be a situation that the equipment can only be recognized as USB 2.0 device.

The data cable is Type-C to Type-C.

We have contacted the SOC manufacturer to help analyze the cause of the problem. The following is the analysis result provided by them:

1) We found that the waveform of TX2 on the PC side after passing through Redriver was abnormal, and we did not detect our RX terminal connection. We suggest consulting TI's FAE to see what parameters the RX DET in the following figure is and whether it is adjustable.

2) Additionally, we suggest to modify the EQ CFG configuration and gradually increase it to see if there is a possibility of connection. When there is no Redriver, there is no problem. and when Redriver is added, there is a problem. We suspect that the signal after Redriver is not compatible with the RX of the device. 

Do you have any suggestion for this problem? The schematic is as below:

Thanks,

Best Regards

Hi,

1. The RX detect parameters on the TUSB1002A are not adjustable. The SoC should enable terminations on the RX differential pins first. Once these terminations are present, our re-driver will go into active mode.

Lumina Gui said:

we did not detect our RX terminal connection

I'm not sure what "RX terminal connection" is referring to. The SoC should enable RX terminations by default if it is acting as a USB host and providing VBUS. Our re-driver will detect these terminations from the host and enable the corresponding receiver terminations on the re-driver.

When the RX terminations are detected from both the USB host and device, the TUSB1002A will go into active mode.

Do you see LFPS passing through our device when a connection is made? If so, RX detect is working correctly.

Lumina Gui said:

Additionally, we suggest to modify the EQ CFG configuration and gradually increase it to see if there is a possibility of connection. When there is no Redriver, there is no problem. and when Redriver is added, there is a problem.

This could be an EQ issue. I see in your schematic that you are maxing out the EQ settings which is typically not needed unless your channel is extremely lossy. Can you try lowering the EQ settings and see if it helps?

Additionally make sure MODE is left floating like you described in your post.

Best,

Shane

Hi Shane,

We adjusted the EQ from the highest to 0, but this problem still exists. But if the R1 resistor is connected, there will be no problem. While connecting the R1 will bring more serious USB recognition problems (Unplugging the USB, the device icon on the computer will always exist.)

Shane Hauser said:

Can you try lowering the EQ settings and see if it helps?

Regarding this issue, I have posted a new post on the E2E forum. I have included a detailed description of our testing update in that post, and we can discuss the question on it.

The new post link is as below:

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1450858/tusb1002a-usb2-0-usb3-0-recognition-issues

Best Regards,

Hi Lumina,

Thank you for the update. I see my colleague has responded to your new thread already. Let me know if you have any questions.

Best,

Shane