TUSB8041: TUSB8041 Briefly functions before shutting down

Hi John:

    Type-C port is hub upstream port or downstream port?

   Can you send schematic in white background?

Best

Brian

The Type-C port is the upstream port. 

Here are the SCH's in black and white

for hub, USB_Vbus should be round 0.5v,  so the divider  should be 25k/10k, pin49 TEST pin hould be grounded.

for TUSB1142, how do you control  EN pin and SLP_SO#?

Best

Brian

Hi Brian, I modified the divider values for VBUS to provide 0.5V, the behavior is still observed. The EN pin for the TUSB1142 is connected to the PLG_EVENT pin of the TPS25730D which is pulled high when a USB cable is connected. I did retroactively add a strong pull-up resistor to this pin to ensure it is enabled, although according to the TUSB1142 data sheet, this pin should have an internal 500K pull-up as well. The SLP_S0# pin is pulled up with a 1K resistor, R113. 

Can you  probe  the VBUS_IN and  3.3v supply for hub? I like to see the relationship between them.

Best

Brian

Hi Brian, I will do that and post the scope shots of VBUS_IN. One update for you, it seems like part of the issue was a USB PD capability mismatch. When testing with a powered USB-C Hub, the USB 2 devices (two microcontrollers and an FT2232H) boot up as expected and I am able to connect to them. However, the USB3 device (FT600) does not work properly, and in windows control panel it shows an unrecognized USB device in link compatibility mode and it fails to enumerate the FT600. The Hub also gets quite hot despite there being no active data transfer. I've triple checked the FT600 USB connections and cannot find anything that would indicate it is at fault, so I believe the hub is to blame for the failed USB3 connection. I've attached the FT600 schematic for reference. 

Thanks!
John

Hi Brian, below are the scope shots for 3V3 and VBUS_IN. With the updated divider, VBUS_IN rises to 617mV.

Best, 

John

from above picture , Vbus seems  0.5v, did you measureed at hub USB_VBUS pin?

What  I want is VBUS_IN from type-C connector.

Best

Brian

Hi Brian, 

Apologies for the confusion, below is the scope shot of VBUS from the USB-C connector and 3V3.

Best, 

John

Waveform looks ok.

Can you remove  ground  for  PWRCTLx  pin?  PWRCTLx should be active high, but it was forced to low.

or you can pull FULLPWRMENT pin to high to disable  power switching.

Best

Brian

Hi Brian, 

Unfortunately I am unable to disconnect PWRCTLx from GND, but I did add a pull-up on FULLPWRMENT which seems to have made some difference. Now when the board is powered up without a host PC connected it only draws 1.2W and the hub chip gets slightly warm. However, when connecting to a host PC, the power draw spikes to 3.4W and the hub gets very hot. I also still get the error message in device manager saying there is an unknown USB device link in link compliance mode. All of the USB 2.0 devices connected to the hub still function. 

Best, 

John 

Can you try  to  pulldown PWRCTL_POL to make it active low?

Best

Brian

Hi Brian, 

This seems to have helped with the power draw slightly. Without a host PC connected it is 1.2W and with a host PC it goes up to 2.8W, however the USB 3 connection still does not work and goes into an error state while all USB 2.0 devices continue to function. 

I have also noted that in one orientation of the USB-C connector, when PLG_FLIP is HIGH, the USB connection appears to be down, and all devices do not show up, but when it is flipped and PLG_FLIP is LOW, the USB 2 devices show up and the USB 3 error is seen in device manager.

Best, 
John

Do you have USB analyzer?

Best

Brian

Unfortunately not on the scope I have, however my university lab may have a logic analyzer or scope that can do USB analysis

One note, I did fix the USB cable orientation issue, it ended up being an issue with the soldering of the USB port, the solder did not make it fully though the PTH's for the connector. This seems to have solved the USB link error, however the SS_SUSPEND pin is HIGH on the Hub and the FT600 does not show up in device manager, only the USB 2 devices. 

So USb3 working for hub upstream?

Best

Brian

I believe so, however the USB3 downstream connection to the FT600 is still nonfunctional and the hub continues to dissipate a significant amount of power when connected. I will take a very close look at the FT600 connections to make sure I don't have an error there causing these issues. 

Thanks,

John  

Hi Brian, 

I believe I found the issue. In my schematic I have SSTX from the Hub going to SSTX on the FT600 and SSRX going to SSRX. I have not yet swapped the pairs, however assuming the hub is meant to be used with a type a USB 3 cable which swaps the pairs, I think this is likely the issue. I will report back once I rework the board and swap the pairs. 

Best, 

John

AC  cap is needed as well on SSRX.

Best

Brian