TUSB217A: USB2 cannot work (TI TUSB217A)

Hi Every,

Have you checked the waveforms coming from the ENA_HS and CD pins when plugging in a USB2.0 device? If you can, please take a look at those waveforms and compare them to the waveforms shown in this app note: TUSB21xx High-Speed Signal Quality Test Modes . If they do not, please make sure you are following test procedures described in section 9.2.2.1 of the datasheet.

Please let me know what you find, and if you still need help, we can go from there.

Thanks,

Ryan

We remove the L60 and L61which is the bead connect P3V3_STBY to VCC, the server can recognize keyboard via Front cable on USB3.0/ USB2.0.

Please help to double check the schematic if we misunderstand something.

If you need more information, please let us know.

Hi Every,

Happy to hear that fixed it. I tried to check it on my end, but the pictures you sent were too small to actually see/check. I sent you a friend request on E2E, if you could accept that and send me the images through a zip file in a private message, it would let me double check your schematic for you and I would appreciate it.

Thanks,

Ryan

Hi Ryan,

I will send the schematic to you by email. please check it .

Regards,

Mark

Thank you for your help, Mark.

Hi Every and Mark,

Assuming you are using Boost level 2, DCP, that R832/R836 are being implemented, and that the RXsen level is meant to be high, I do not see any issues in the redriver schematics.

If the ferrite beads are being taken out/replaced, I would recommend running some test to ensure there is not too much noise coming from the power supply. The ferrite bead is meant to filter that noise out, so if there noise is too strong without the bead, you may need to look for a different option or try different bead values.

Please let me know if you have any questions or need any clarification.

Thanks,

Ryan

What is the value of R832/R836 to being implemented? Both of them are 27K?

About the ferrite bead, do you have any suggestion on this material or what is the characteristic of ferrite bead I neet to wariness.

Thank you,

/Every_Hsiao

Hi Every,

Sorry, I meant to say are NOT being implemented, there should only be 27K resistors at R831 and R837.

As for the ferrite bead, they are used primarily to filter out unwanted noise and frequencies that may prove detrimental to a signal or device. In this case, if you wished to try to implement one into the system even though removing it seemed to fix the problem, I would recommend trying something lower in resistance than the one used in the example schematic. However, as I said, if the test with the device show no errors, it may not be necessary.

Please let me know if you have any other questions

Thanks,

Ryan

We have poped R831 and R837 with 27K resistors in current design, but the USB 2.0 function is still unstable, plugging USB3.0 USB key we can find the device, but we can’t find a keyboard USB device.

I'm curious why that when we remove the ferrite bead which connects P3V3_STBY to VCC, the server can recognize keyboard via Front cable on USB3.0/ USB2.0. Does the re-driver still work when we remove the ferrite bead?

Do you have refered schematic design for our reference?

/Every_Hsiao

Hi Every,

You can find a reference schematic design on the datasheet of the TUSB217A.

Is the unstable functionality happening with and without the ferrite bead attached? Or only with? Also, what are the specifications on the ferrite bead being used, I.E Impedance? If the bead being used is the one shown in the schematic, then the impedance of it is 600 ohms which is much higher than what is recommended, 100 ohms.

Also, how much voltage are you seeing after going through the ferrite bead?

If the power supply being used for the redriver does not produce high-frequency noise, then you may be able to work without it otherwise, I would recommend it.

Thanks,

Ryan

HI Ryan,

The unstable functionality happening only with ferrite bead attached. As you said, the impedance of it I used is 600 ohms. We will replace it with 120 ohms and try again.

However, if the functionality work normally without ferrite bead, does it mean the USB3.0/ USB2.0 not to need the TUSB217A to provide more driving power?

/Every_Hsiao