TUSB1064: Application issues.

Hi,

Thanks for reaching out. Are you able to show the schematic for the entire AUX path? The TUSB1064 should not attenuate the AUX signals so I'd like to be sure the connections are correct.

You can attach the schematic here, or if you want to share this privately, you can direct message a pdf file on E2E by accepting my friendship request.

Best,

Shane

HI shane，

The simple block diagram is as follows

we think that connections are correct，Because only when we use 5 meters or 10 meters TYPE-C AOC cable will appear no picture phenomenon，When there is no picture, USB is fine；

TYPE-C.pdf

Hi Michael,

When you plug the display in to your DP host, does the host recognize the display?

I am curious whether the AUX or the Main link is the issue. If you're able to see the display but no video is showing, it could be that the Main link lines are attenuated too much.

Best,

Shane

The host can't recognize the display or get an  incorrect edid

Our clients have also done some tests

Lenovo T14 Gen 1 (Video does not pass)

Lenovo T16 Gen 2 (Video does not pass)

MacBook Pro M1 2020 – Sonoma 14.2.1 (Video does not pass)

MacBook Pro M1 2021 – Sonoma 14.5  (Video does not pass)

Intel NUC – 12^th Gen i5 – Windows 10 (Video does not pass; you can see it trying to synchronize, but the signal never locks)

Intel NUC – 13^th Gen i5 – Windows 11 (Video does not pass; you can see it trying to synchronize, but the signal never locks)

 The only computer that has successfully worked is a Mac Mini M1 2020 - Sonoma 14.5 (Video & USB work)

Hi Michael,

1. Can you probe the AUX lines near the 1064 and check the common mode voltage when your USB/DP source is plugged in? The TUSB1064 requires the common mode voltage on AUXP to be min of 0 and max of 0.4V. The common mode voltage on AUXN is required to be min of 2.7 and max 3.6V.

2. If the CMV is ok, are you seeing any change in the AUX signal between the SBU input and AUX output of the TUSB1064 when using the long cable? Do you see any signal at the output?

Best,

Shane

HI Shane

when the USB/DP source is plugged in，

 the common mode voltage on AUXP is 0.46V and AUXN is only 0.38V；

Some waveform will be lost after 1064 when we used long cables.

Hi Michael,

The AUXn common mode voltage is outside of the spec for our device. AUXn should bias near 3V due to the 10:1 resistor divider between the DP source and DP sink:

You have the sink-side connection right so I want to confirm you're measuring near the 1064 (between the 1064 AUX pins and the AC coupling capacitors).

Is the common mode voltage different with the short cable vs the long cable? If so, you may want to try a different long cable and see if AUX passes.

Best,

Shane

HI Shane

The common mode voltage of the short cable is 2.7-3V. We've tested a lot of cables and two companies have abnormal cable common-mode voltage.Other cables are fine.

Hi Michael,

This seems like an issue with the abnormal cables. Do you have a long cable with good CMV readings?

If not, you may need another cable. Do the abnormal cables work to pass video directly from the source to a DP video sink? (without the 1064 board in between)

Best,

Shane

yeah， thanks Shane，We have informed the cable factory of these conditions。They'll modify the cable。

Thanks again

Best,

Michael