TUSB211A: Some question about the application of TUSB211A

Hi Lumina,

Lumina Gui said:

1) Because our eye diagram test failed (Host mode), so I would like to ask if TUSB211AI can correct the eye diagram? Or is there any other p/n for recommendation? Our architecture is as follows: the motherboard is connected to the USB connector through an FPC, and we plan to place the re-driver on the FPC near the USB connector end.

Yes, the TUSB211A would be an applicable choice for fixing this setup. What is the total distance from host to the eye test point, just to confirm?

Lumina Gui said:

2) TUSB211AI has D1P/N and P2P/N. We would like to confirm which end is connected to the CPU (HOST) end and which end is connected to the connector (device) end. 

Due to the two of the three explanatory diagrams on the datasheet have the same connection, but one has a different connection. The three connection diagrams are as follows:

The TUSB211A is bi-directional, so there is no need to worry about which end is connected to host or device. The only requirement is that DP and DM are properly matched/connected.

Lumina Gui said:

3) The following is the suggested footprint on the spec. We need to confirm whether the footprint D1P should be directly connected to D2P and D1M should be directly connected to D2M. Is this correct?

The TUSB211A passively boosts any signals that run underneath it, and can be placed over a USB2 trace to inject current into the signal, boosting it. As such, D1/2P and D1/2M should be connected to each other beneath the device via the USB data lane trace, as highlighted in the picture you sent.

Please let me know if you have any other questions, or need further clarification!

Thanks,

Ryan

Dear Ryan,

Thanks a lot for your reply. Regarding the question you mentioned, our response is as follows:

Ryan Kitto said:

What is the total distance from host to the eye test point, just to confirm?

We just would like to know the distance from HUB to TUSB211A and the distance from TUSB211 to USB connector. Do you have any suggestions or are there any restrictions on the overall length?

Anyway, do you have any suggestions for the placement of TUSB211A? Do we need to place it in front of the EMI filter (position 1) or behind the EMI filter (position 2)?

Thanks,

Kind Regards

Hi Lumina,

Lumina Gui said:

We just would like to know the distance from HUB to TUSB211A and the distance from TUSB211 to USB connector. Do you have any suggestions or are there any restrictions on the overall length?

The TUSB211A can support of to 5 meters worth of cable/trace-length for compensating the signal. If the distance is very short, however, then there is a chance that adding a redriver can cause over-compensation.

Lumina Gui said:

Anyway, do you have any suggestions for the placement of TUSB211A? Do we need to place it in front of the EMI filter (position 1) or behind the EMI filter (position 2)?

We recommend as close as possible to the connector, so if possible, position 2 would be best.

Please let me know if you have any other questions.

Thanks,

Ryan