TUSB8041: TUSB8041 doesn't come up on some boards at -40deg

Balaji Padmanaban

Intellectual 705 points

Part Number: TUSB8041

HI All,

I have gone through all the issues regarding the TUSB8041 in the forum.

I need ideas for this.

One some boards i have,

the USB 2.0 and 3.0 HUB doesn't show up in Linux only at -40deg power on.

I have not probed the signals at -40deg in the thermal chamber which i will do it.

I have few ideas or thoughts , which some body has to tell me if incorrect:

Observation:

1.The I2C works registers dumps at -40deg is yet to be taken but i2c works at -40deg

2. I cannot do a hard reset of the hub but i trued resetting the whole unit which still doesnt show the Hub @ -40deg

3.Soft reset @ -40deg over i2c doesnt work

4.The hub 0XF8 register is set to 1 to start the hub, i verified this.

5.The issue doesnt occur on all cards 1 out 5.

My suspects

1. Corrected the VBUS pin 48 release after GRST using a modification but still the issue.

2. Does the thermal pad cause issues?(the layout is done correct with vias stiched), may be not enough paste on this card?

3.Does not the crystal start oscillation?

4. The card is con formal coated so its getting difficult to figure this out

5. Am yet to probe the suspend signal(pin 45) to check if things are okay.

Any thoughts?

BR,

Bala

over 5 years ago

0 Balaji Padmanaban over 5 years ago

Intellectual 705 points

USB HUB Issue.docx

0 Balaji Padmanaban over 5 years ago in reply to Balaji Padmanaban

Intellectual 705 points

This is the schematics and PCB

0 JMMN over 5 years ago in reply to Balaji Padmanaban

TI__Guru 60870 points

Hi Bala,

Does this problem only occur at -40C? Is both USB 3.0 and USB 2.0 consistently failing? Or sometimes one or the other?

Regards,

JMMN

0 Balaji Padmanaban over 5 years ago in reply to JMMN

Intellectual 705 points

Yes only at cycles when i power on at -40deg.

and it doesnt recover when i power cycle at -40deg.

The junction of TUSB8041IRGCT should be hotter than -40deg when turned on at -40deg.

I dont have data of whats the case temperature when the Unit is at -40deg.

Attached is my thermal cycle

0 Balaji Padmanaban over 5 years ago in reply to Balaji Padmanaban

Intellectual 705 points

It happens for both USB2.0 and USB3.0 hub.

They dont show up in the lsusb and the i2c work on some case and some case not.

0 Balaji Padmanaban over 5 years ago in reply to Balaji Padmanaban

Intellectual 705 points

as well today i saw only USB3.0 (0451:8140)hub up coming up but not USB 2.0 showing 0451:8142

i have taken a screen recording of the issue.

I have a working case dump of the I2c registers as below.

0 Balaji Padmanaban over 5 years ago in reply to Balaji Padmanaban

Intellectual 705 points

At 55 deg if turn on i can both the hubs on this box and issue is different across boxes.

here is a dump on a working condition

~ # i2cdump -y 2 0x47 b

0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef

00: 00 51 04 40 81 1c 00 0f 0f 00 20 00 00 00 00 00 .Q?@??.??. .....

10: 02 80 90 c5 00 da 52 f5 c6 16 27 c2 b6 c9 d0 00 ????.?R???'????.

20: 09 04 18 00 00 00 00 00 00 00 00 00 00 00 00 00 ???.............

30: 41 00 31 00 30 00 34 00 30 00 30 00 37 00 31 00 A.1.0.4.0.0.7.1.

40: 44 00 43 00 36 00 34 00 00 00 00 00 00 00 00 00 D.C.6.4.........

50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

d0: 1e 1e 1e 1e 1e 00 00 00 18 18 18 18 18 00 00 00 ?????...?????...

e0: 04 04 04 04 04 00 00 00 77 77 77 77 77 00 00 00 ?????...wwwww...

f0: 00 00 00 00 80 80 80 80 01 12 00 00 00 00 00 00 ....??????......

0 JMMN over 5 years ago in reply to Balaji Padmanaban

TI__Guru 60870 points

I'm checking on possible root causes with the internal teams,

Can you confirm if the clock is starting up at the correct frequency / swing?

Has high temp been tested? Were there any issues?

Regards,

JMMN

0 Balaji Padmanaban over 5 years ago in reply to JMMN

Intellectual 705 points

Nope, the high temperature is fine.

Am yet to probe the power clock and reset at -40,

I will send you the waveform at 25deg,-40degC,70degC.

BR,

bala

0 JMMN over 5 years ago in reply to JMMN

TI__Guru 60870 points

Ok, and I just wanted to confirm you are using the industrial version of this part? The commercial version only supports 0C-70C,

0 Balaji Padmanaban over 5 years ago in reply to JMMN

Intellectual 705 points

Yes thats correct . TUSB8041IRGCT

I will check the top marking on these now

0 JMMN over 5 years ago in reply to Balaji Padmanaban

TI__Guru 60870 points

Also, you mentioned that 1 out of 5 units fail? Do they all pass at -30?

0 Balaji Padmanaban over 5 years ago in reply to JMMN

Intellectual 705 points

So far 5 out of 10.

I was also able to reproduce the issue at 70deg after lot of attempts.

When i bring back to 25 both USB 2.0 and USB3.0 comes back

0 JMMN over 5 years ago in reply to Balaji Padmanaban

TI__Guru 60870 points

I'm surprised you are able to see issues at both high temp and low temp. In all cases do both USB 2.0 and USB 3.0 fail to connect? Or just one or the other? If you toggle USB_VBUS low and then high, does the hub appear? When you bring the system back to 25C, do you do a reset or does the hub just connect once the temperature returns to nominal?

REgards,

JMMN

0 Balaji Padmanaban over 5 years ago in reply to JMMN

Intellectual 705 points

Some cases USB2.0 & USB3.0 and at some cases its USB2.0 that doesnt come up.

I dont have control over VBUS or Reset pin. they are power on reset controlled.

The USB HUB some time recovers at 25deg and some time doesnt.

Its very random, am not able to characteristic the behavior.

Am thinking of the solder paste underneath the USB HUB during reflow being very low.

0 JMMN over 5 years ago in reply to Balaji Padmanaban

TI__Guru 60870 points

Hi Balaji,

Yes, insufficient solder paste can cause a lot of varying device issues since it will impact device temperature and acts as the main ground for the hub. Are you able to check it with an x-ray? Or rework a board to add more and retest?

Regards,

JMMN

Interface

Interface forum

TUSB8041: TUSB8041 doesn't come up on some boards at -40deg