TPS25730: TPS25730: issues with USB Full Speed Data on some USB C ports.

Kirk Vrigian

Part Number: TPS25730

Tool/software:

Hi,

One of our designs is currently using the TPS25730D with a FT232RNL. In terms of USB-C it is Sink-only (hence the choice of TPS25730D) and USB data is UFP only.

Using some of the USB-C wall warts, we are able to successfully negotiate 9V, all USB-A ports work & some USB-C ports work.

However, on some Windows 11 devices using the USB-C ports, the VBUS will be active and +5V on our device, but the virtual com port won't enumerate or will connect & disconnect. The device manager will refresh, but no virtual com port will show up. If I use a USB-A to USB-C cable, everything works fine. I have also completely removed the TPS25730D, shorted the vbus line & soldered 5.1k pulldowns on the cc pins, this also fixes the issue.

Attached are my USB PD & USB serial converter schematic. The converter is self-powered, not using vbus.

4 months ago

0 Aya Khedr 4 months ago

TI__Mastermind 30332 points

Hi Kirk,

Thank you for reaching out!

Do you have PD logs of the observed behavior?

Best Regards,

Aya Khedr

0 Kirk Vrigian 4 months ago in reply to Aya Khedr

Prodigy 40 points

I will get back to you on this, I'm assuming logs from a logic analyzer on the CC line?

0 Aya Khedr 4 months ago in reply to Kirk Vrigian

TI__Mastermind 30332 points

Hi Kirk,

Yes, I would like to see the PD messaging that is occurring between the port partners.

Best Regards,

Aya Khedr

0 Kirk Vrigian 4 months ago in reply to Aya Khedr

Prodigy 40 points

Hi Aya, I have done 3 captures, each with a capture file & raw export .csv.

1) USB working 5V surface pro
2) USB working 9V wall wart
3) USB PD failed with PC.

0 Kirk Vrigian 4 months ago in reply to Kirk Vrigian

Prodigy 40 points

7418.USB PD CC negotion captures.zip

0 Aya Khedr 4 months ago in reply to Kirk Vrigian

TI__Mastermind 30332 points

Hi Kirk,

I noticed you provided Saleae logs, did you use a particular decoder to interpret the CC messaging?

Best Regards,

Aya Khedr

0 Kirk Vrigian 4 months ago in reply to Aya Khedr

Prodigy 40 points

Should i use something else? I used the PD3.1 Analyzer in the Saelae store. In the logic app under extensions. Repo for it is located here, GitHub - eugenecyyeh/Saleae-PD3.1-analyzer.

I also believe the capture saved the bits per frame for 8 bit per transfer, but the analyzer requires "1 Bit per Transfer".

0 Aya Khedr 4 months ago in reply to Kirk Vrigian

TI__Mastermind 30332 points

Hi Kirk,

I will try loading in the extension provided and let you know if the information is sufficient. Typically we recommend using a PD analyzer tool (like a PowerZ for example).

Best Regards,

Aya Khedr

0 Kirk Vrigian 4 months ago in reply to Aya Khedr

Prodigy 40 points

Okay, I will get one, is there anything in particular you need from the logs?

0 Aya Khedr 4 months ago in reply to Kirk Vrigian

TI__Mastermind 30332 points

Hi Kirk,

I would be looking for the PD communication between the devices for the 3 use-cases you mentioned.

Best Regards,

Aya Khedr

0 Kirk Vrigian 3 months ago in reply to Aya Khedr

Prodigy 40 points

Hello Aya,
I've attached the captures; there are 6 in total. 3 source devices and 2 load devices.

1) 9V wallwart with our product.
1a) 9V wallwart with TPS25730 Eval board
2) PC with our product (usb port enumerates).
2a) PC with TPS25730 Eval board.
3) Surface go with our product (usb port doesnt enumerate).
3a) Surface go with TSP25730 Eval board.

The interesting thing i saw is with the pc that enumerate it requests a hard reset 3 times and that's it, but the 5V is still present.

Zpower captures.zip

0 Aya Khedr 3 months ago in reply to Kirk Vrigian

TI__Mastermind 30332 points

Hi Kirk,

Thank you for capturing the logs, these are helpful for debug.

I will review them and get back to you with feedback tomorrow.

Best Regards,

Aya Khedr

0 Kirk Vrigian 3 months ago in reply to Aya Khedr

Prodigy 40 points

Hi Aya,

Any update on this? I've actually tried integrating this same PD design with a Atsam21G18A and it's still doing the same thing with the same failing pc's.

0 Kirk Vrigian 3 months ago in reply to Kirk Vrigian

Prodigy 40 points

Could it possibly be a timing issue? Say if the pd negotion takes too long and the usb 2.0 data lines try to enumerate too soon?

0 Kirk Vrigian 3 months ago in reply to Kirk Vrigian

Prodigy 40 points

I tried delaying the usb drivers from starting up until usb vbus was present, this did not resolve the issue.

0 Ghouse Mohiuddin23 3 months ago in reply to Kirk Vrigian

TI__Expert 8050 points

The FT device maybe showing termination early. I am not completely sure how we can help on this. You should reach out to the FT team to see if they have any ideas. As you can see the PD controller have no interaction with data pins. One thing you can possibly try is timing on the supplies to the USB2.0 device. Maybe power gate them until VBUS is stable.

+1 Kirk Vrigian 2 months ago in reply to Ghouse Mohiuddin23

Prodigy 40 points

I believe I resolved the issue, and it seems to be a design choice issue, I noticed on the logs during pd negotiation, the TPS25730 flags the USB comm capable bit as 0. I see that bit 26 is reserved and cannot be changed. So, the TPS is telling the host it is not usb data capable and the source is disconnecting usb communication.

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TPS25730: TPS25730: issues with USB Full Speed Data on some USB C ports.