TUSB8041: Request for Power-up timing and schematic review

Hi Jeffrey:

  Are there AC caps between hub upstream port and host?

Regards

Brian

Hi Brian,

Let me check it with customer, and then I will update it. And Is there any issue on power-up sequence/timing?

Regards,

for power sequence, time between 3.3v and 1.1v is pretty long, but I don't think it's a issue.

Best

Brian

Hi Brian,

I've got the following answer  from another engineer at TI regarding the TUSB8041 power sequence. He says that 1.1V should start earlier than 3.3V". but you're saying  it doesn't matter 3.3V is supplied earlier than 3.3V.  

 " For power on sequence, there is no power on sequence if you can external control GRSTz.

   If just external cap on GRSTz pin, then 1.1v should start early than 3.3v."

in the spec sheet, if VDD33 supply is stable before the VDD11, Active reset is required.

(does the Active reset mean an external reset? not the internal reset( using GRSTz pin))

And,  there is no power - on relationship between VDD33 and VDD if the VDD11 must be stable minimum of 10us before the VDD33.

Could you please clarify:

if 3.3V is supplied before 1.1V, is it okay to adjust the internal reset by adding a capacitor on the CRSTz pin?

Or, we have to change the circuit so that VDD11(1.1V) can be supplied before VDD33(3.3V)?

Regarding your question about AC cap between hub upstream port and host,  our product use the TUSB522p equalizer between Host and USB3.0HUB and use the 0.1uF AC cap.

Hi  Seungman:

      Active  reset means  using external  GPIO signal to control GRSTz pin and passive reset means adding  extermal capacitor on GRSTz pin.

     Since GRSTz pin is pulled up with 3.3v internally, GRSTz will go high after 3.3v is  on. If 1.1v is  on after 3.3v ,  GRSTz .could go high before 1.1v and hub may not get enough time for reset  if the  cap  value  is not big  enough.

    If  using active reset ,  there is no power sequence since  you can control  reset signal  to keep GRSTz low until  3.3v and 1.1v stable.

    let me know if you still have question about power sequence.

Best

Brian

Seungman Son said:

Regarding your question about AC cap between hub upstream port and host,  our product use the TUSB522p equalizer between Host and USB3.0HUB and use the 0.1uF AC cap.

Can you send TUSB522P schematic as well?

Best

Brian

Thank you for clarifying. in our case, we are using the 1uF cap value on the GRSTz pin and the power sequence is as follows. the GRSTz keeps a low for 14ms until 3.3 and 1.1V stable. If so, I think there is no problem. Do you think we need an Active reset?

I think we are having trouble uploading the schematic due to our security system, so I am sending you a captured schematic.

this is for schematic for TUSB522p 

and  this is our USB connect (CN1) for Host.

Hub power sequence looks good, you don't need to change it to  active  Reset.

Best

Brian

upstream port schematic looks good,

can you send downstream port schematic for review?

Best

Brian

here is our downstream port.

What is difference  between DN1_Vbus_out and  DN1_Vbus?

 DN1_Vbus was connected to the USB_VBUS S/W(UU2) output and its output is connected to DN1_VBUS_OUT through a FET switch.

ok,  let's back to  issue  "This device is not recognized intermittently on the device manager"

did  you mean the hub not recognized or  the device  on Hub downstream port not detected?

Regards

Brian

According to our customer, they've confirmed that the hub not recogmoized intermittently.  I think if there are no major problem in our circuit, the issue may be that our 1.1V was supplied too late. At that time, our product 1.1V was supplied around 300ms later than 3.3V to the TUSB8041. So we first changed the circuit to supply 1.1V power without delay and almost like 3.3V. Since the symptom is not well reproduced, we will review it more and contact you again if the problem reprouce again. Thank you very mush for your support.

Hello Brian,

It seems that the problem of not recognizing the TUSB8041 has not been solved. This time, it is not related to the power sequence. If repeatedly connect and disconnect only the USB3.0 data while the power is already supplied stably, the problem of the host (PC) not recognizing the TUSB8041 occurs intermittently. What should I check when the issue occurs?

I will look at again for  this issue.

Best

Brian

1: make sure Test pin is  grounded.

2: when issue happens, did crystal oscillate?

3: Can customer  try TUSb8041A, it's P2P with TUSB8041.

Best

Brian

1. NO. currently RU3 is open. it is not conneted to GND. Is it mandatory to connect it to gnd?

2. Even when there is a problem, the cystal oscillated.

3. At this point, it is impossible. Why do you want to try to TUSb8041A?

Seungman Son said:

NO. currently RU3 is open. it is not conneted to GND. Is it mandatory to connect it to gnd?

it's mandatory.

Seungman Son said:

At this point, it is impossible. Why do you want to try to TUSb8041A?

TUSB8041A  fixed  some bugs in TUSB8041.

Best

Brian

1. OK, we will add 4.7Kohm on RU3.  

 2. Could you please let me know which bugs were fixed?

Thank you for the infomation. but I don't think TUSB8041A is a good solution to solve the problem that the host (PC) does not recogniz the TUSB8041 intermittently.  Could you please let me know what should I check to find the root cause of issue when the problem was occurred. If you let me know the checkpoints, I will review them and get back to you.

the connector to  TUSB522P  is normal USB connector ? just see if can take USB trace from upstream port,

Best

Brian

the connector (CN1) to TUSB522p is a customized USB connector.
but, we have already conducted the USB3.0 SI Test at the official test lab, and the test result was a no problem.

I mean taking usb  trace by USB analyzer which include usb link training .  SI test is only for electrical  test.

Best

brian

Hi Seungman:

   Can customer take USB trace with analyzer?

Best

brian

I will ask it to customer. but I think it is not available. I will also try it.  the problem is the failure symptoms is occurred intermittently. so it is hard to reproduce the symptoms. Anyway what should we focus on using the analyzer?  I also have never used an analyzer before so I don't know much about it.

Analyzer  is used to record USB traffic between host and device, it's a good way to find the root cause for 3failed USB connection.

Best

Brian

The problem is not reproducible. Anyway, I will review it using the analyzer if the problem is reproducible.

Anyway, thank you for your support!