TUSB8040A System Wakeup Issue

Prescott Siao

Other Parts Discussed in Thread: TUSB8040A

Hi team,

My customer make 60 boards using our TUSB8040A.

There are 15 boards with system wakeup Issue. When they are shounting down the system about 6~10 seccond later the system would wakeup again.

We find out there are some different between the good board and ban board.

We measure the USB2.0 D+/D- of the bad boards, the D+/D- will keep about 148ms as below picture.

Here

Yellow line: S5 signal

Blue line: USB Hub D+

Green line: USB Hub D-

Purple line: Hub Power

For Bad board

1.) After shut down the system, the D+ from high to low is 148ms

2.) Occur J-state tranfer to K-state resume event that will make the system wakeup again.

We measure the USB2.0 D+/D- of the good boards, the D+/D- will keep about 128ms as below picture.

Here

Yellow line: S5 signal

Blue line: USB Hub D+

Green line: USB Hub D-

Purple line: Hub Power

For Good board

1.) After shut down the system, the D+ from high to low is 128ms

2.) No occur J-state tranfer to K-state resume event.

We can fix this issue by remount brand new TUSB8040A.

Is there any issue of the TUSB8040A making this happen?

Regards, Prescott

over 10 years ago

0 JMMN over 10 years ago

TI__Guru 60870 points

Hello Prescott,

This could be an issue with the power down sequence on the TUSB8040A. If the power rails turn off very slowly the TUSB8040A may be powered on enough to interpret the condition in circle A as a wake event.

Regards,
JMMN

0 Prescott Siao over 10 years ago in reply to JMMN

TI__Intellectual 2220 points

Hi JMMN,
Why we could fix this issue by remount new TUSB8040A if this issue with the power down sequence?
Regards, Prescott

0 JMMN over 10 years ago in reply to Prescott Siao

TI__Guru 60870 points

Hello Prescott,

The TUSB8040A behavior is undefined while is it only partially powered. Some TUSB8040A devices may continue to function at very low power, others will not. Can you confirm that the TUSB8040A is in the process of being powered off when this problem occurs?

Thanks,
JMMN

0 Sam Ting over 10 years ago in reply to JMMN

TI__Expert 3580 points

Hi JMMN,
We just confirmed that the VDD33 and VDD11 were alive when this problem occurred.
Best regards,Sam Ting

0 JMMN over 10 years ago in reply to Sam Ting

TI__Guru 60870 points

Can you confirm the VBUS level while DP is decaying in the system?

If VBUS is still high, hub devices may interpret the decaying DP as a USB reset event. In response, the hub will drive a Chirp K (~1.5 ms pulse) on DM in response to the perceived USB reset causing a system resume.

0 Sam Ting over 10 years ago in reply to JMMN

TI__Expert 3580 points

Hi JMMN,

USB_VBUS is still at 5V while DP in decaying in the system.

Best regards,

Sam

0 JMMN over 10 years ago in reply to Sam Ting

TI__Guru 60870 points

If the TUSB8040A is in a low power state it will have DP pulled high. It should continue to have DP pulled high if the hub remains powered and VBUS is on. We need to understand why DP is decaying in the system. Is it being terminated by the host?

Interface

Interface forum

TUSB8040A System Wakeup Issue