TUSB8020B: Hub enumeration fails; hub chip remains asleep/inactive

Kurt Widhalm

Part Number: TUSB8020B

I have laid out my PCBA with an implementation of this hub chip similar to the TUSB8020BPHP REVA Evaluation Module.

I have confirmed that the Power input pins (1.1 & 3.3VDC) all receive power.

DP/DN UP all read 0VDC when powered and attached to the host, so no handshake attempt is being made (no internal pull-ups active)

Power control to downstream ports is working (Ports have 5VDC active through individual current limiters).

GRSTZ (pin 11) is floated over a 1uF capacitor to ground. TEST (pin 10) is pulled down to ground by 1k resistor. I read 0.56VDC on VBUS-Detect (pin 9) when attached to upstream USB host.
Am I missing a key enable pin or inadvertently triggering some safety shutoff for the hub?

over 2 years ago

0 Kurt Widhalm over 2 years ago

Prodigy 50 points

6305.TUSB8020Schematic.pdf
Re-uploaded schematic, previous page was blank

0 Brian Zhou over 2 years ago in reply to Kurt Widhalm

TI__Guru*** 146715 points

so upstream port is not working? does crystal working?

Best

Brian

0 Kurt Widhalm over 2 years ago in reply to Brian Zhou

Prodigy 50 points

No, upstream port is not working.
I haven't had a chance to test it on the scope yet, but a slow multimeter doesn't show any floating voltages on the clock pads.

for my first revision of this assembly, I populated the clock with NX3225GA-24MHZ-STD-CRA-1 instead of ECS-240-18-30BQ-DS. Will replace part once it arrives to see if that solves it.

Brian- Do you see anything with my settings resistors which might be keeping the chip disabled? Gang-mode / power-enable / test / reset?
is this chip capable of working as-is, or is there an internal otprom that needs to be set for it to function? (I don't have this connected to any SPI devices)

0 Brian Zhou over 2 years ago in reply to Kurt Widhalm

TI__Guru*** 146715 points

I didn't see anything in schematic could cause hub stop working.

1; pls use scope to check crystal clock, meter can't tell.

2: what voltage on USB_Vbus?

Best

Brian

Interface

Interface forum

TUSB8020B: Hub enumeration fails; hub chip remains asleep/inactive