TUSB2036: TUSB2036 downstream port working intermittently

Miteshkumar Dalabhai Patel

Intellectual 2490 points

Part Number: TUSB2036
Other Parts Discussed in Thread: PCM2912A

Hi Team,

One of my cusotmer is working on project for which they have used TUSB2036 - 2 port configuration.

They are using TUSB2036VFR as a USB hub in display design. Two downstream USB devices are connected to the hub:

USB touch
USB audio codec (PCM2912A)

Issue:
When audio playback starts, the USB touch device stops working completely. When audio playback is stopped, touch functionality resumes automatically. This issue is consistently reproducible.

Notes:

Audio works correctly without issues
Touch works normally when audio is inactive

They would like guidance on below points:

Any known limitations or errata with TUSB2036VFR for simultaneous USB audio and touch operation
Recommended configuration or design changes for this use case

Please find the schematic attached for reference.

1 month ago

0 Brian Zhou 1 month ago

TI__Guru**** 155010 points

Hi Sir:

TUSB2036 is full speed hub, it does not has enough bandwidth to support both audio and touch device. It's better to use high speed hub like TUSB4020B.

Regards

Brian

0 Miteshkumar Dalabhai Patel 1 month ago in reply to Brian Zhou

TI__Intellectual 2490 points

Brian,

As per customer, their proto board was working fine with both functionality simultanously. When they have removed some of the other functioanlty & made smaller version of board they found this issue. Note that they havn't changed anything on Hub side. Also note thta both are working independtly.

I will forward this thread to them & they will continue with their observations.

Regards

Mitesh

0 Ryan Kitto 1 month ago in reply to Miteshkumar Dalabhai Patel

TI__Mastermind 46830 points

Hi Mitesh,

Our team is out today on US holiday. Please expect a response on 1/20 after the holiday.

Thanks,

Ryan

0 Brian Zhou 1 month ago in reply to Ryan Kitto

TI__Guru**** 155010 points

Hi Mitesh:

There are couple of issues for the schematic, but not sure which one is the root cause.

1: for type-C port , CC1/CC2 need 5.1k pulldown resistor .

2: for DP0/DM0 and DP1/DM1, DP2/DM2,

22 ohm resistor and 22pf cap are needed for USB2 FS

3: what current for 5V Vbus of port1, how about port 2 Vbus?

Best

brian

0 Prabhanjan Bongarde 1 month ago in reply to Brian Zhou

Prodigy 20 points

Hi Brian Sir,

We have done the following changes as per your suggestion,

1: for type-C port , CC1/CC2 5.1k pulldown resistor .

2: for DP0/DM0 and DP1/DM1, DP2/DM2,

22 ohm resistor and 22pf cap for USB2 FS

But it did not solve our issue

3: We haven't used VBus from IC for port1 and port2, we have given power to the ports directly from 5V lines

0 Brian Zhou 1 month ago in reply to Prabhanjan Bongarde

TI__Guru**** 155010 points

Hi Mitesh:

Hub should work normal with above changes.

Did you get help for audio codec (PCM2912A)? It's pretty complicated device and could change role for USB host or device.

Best

Brian

0 Prabhanjan Bongarde 1 month ago in reply to Brian Zhou

Prodigy 20 points

Hi Brian,

Please note that the audio and touch functions work correctly when tested individually.

However, when audio playback starts, the touch functionality stops responding. The audio continues to work properly in both cases.

Thanks and regards,
Prabhanjan

0 Brian Zhou 1 month ago in reply to Prabhanjan Bongarde

TI__Guru**** 155010 points

Hi Mitesh:

Do you know the audio DAC working at 96kHz/24-bit or 192kHz/24-bit? if running at 192kHz/24-bit , can you try with 96kHz/24-bit ?

Best

Brian

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TUSB2036: TUSB2036 downstream port working intermittently