TUSB4020BI: TUSB4020BI

enquan zhang

Part Number: TUSB4020BI
Other Parts Discussed in Thread: AM3352,

I made a new board which use the USB HUB IC TUSB4020B for two USB interfaces. The TUSB4020B USB up interface is to AM3352. But now AM3352 can not find the TUSB4020B device after the power is up. In other diferent board which is no TUSB4020B, the AM3352 can find USB device, so the software is no problem. I think the TUSB4020B some setting is not correct. Can you help me to find it? Thanks!7607.G90 _ 07 USB_HUB.pdf

over 7 years ago

0 Malik Barton57 over 7 years ago

TI__Guru 64326 points

Enquan,

Here are a few notes and questions on your schematic:

Please pull down both FULLPWRMGT, GANGED and PWRCTL_POL pins with 4.7k resistors.
If this application is to be USB compliant it must be able to report over-current faults on all USB ports.
What does the power up sequence of TUSB4020BI look like? I see you have a active reset on GRSTz. Ensure the assertion/de-assertion of this pin is in line with section 7.7 in TUSB4020BI datasheet.

0 enquan zhang over 7 years ago in reply to Malik Barton57

Prodigy 30 points

Hello,
I have pulled down both FULLPWRMGT, GANGED and PWRCTL_POL pins with 4.7k resistors and after the VDD1.1 and VDD3.3 power up, give the control signal (down and up) the GRSTz. But the system still can not find USB device.
I do not understand what is the meanning of "If this application is to be USB compliant it must be able to report over-current faults on all USB ports." What we need to do for it?

0 JMMN over 7 years ago in reply to enquan zhang

TI__Guru 60870 points

Remove R1548 unless your hub is actually being configured by a SMBUS host.

Regards,
JMMN

0 enquan zhang over 7 years ago in reply to JMMN

Prodigy 30 points

Hello JMMN,
This is OK. Thank you very much.

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TUSB4020BI: TUSB4020BI