TUSB2046B: Unknown Device

Camille poumaredes

Part Number: TUSB2046B

Hello everyone,

I have a problem with my Hub design (see attached file). When I connect it Windows tell me "Unknown Device". I have tried many solution but no one work.

Below the debug solution I made :

- Put pull-up resistor on Overcurrent pin

- Put a RC circuit (R = 2k2 and C = 1uF) on reset

I don't find any other problem I could do. Can you help me?

Camille

Sch_hub.pdf

over 8 years ago

0 Joel Jimenez0 over 8 years ago

TI__Mastermind 18655 points

Hi Camille,
For the RC circuit, use a 15kOhm resistor instead of the 2.2kOhm.
Do you have pull down resistors in the all downstream ports and pull-ups in all OVERCUR terminals?
Regards

0 Camille poumaredes over 8 years ago in reply to Joel Jimenez0

Prodigy 40 points

Hi Joel,

Thank you for answer me.
I have replaced the 2.2kOhm resistor by the 15kOhm but still not working :/
Yes I have pull down resistor in all downstream and all Overcurrent. (You can see this on the schematics attached)

0 JMMN over 8 years ago

TI__Guru 60870 points

Hello Camille,

TSTPLL should be tied low, also there is too much capacitance on the differential pairs. The recommended capacitance is 22 pF, the capacitance in the schematic is 110 nF. For a quick lab test, try removing the capacitors on the upstream port and see if the hub enumerates correctly.

Regards,

JMMN

0 Camille poumaredes over 8 years ago in reply to JMMN

Prodigy 40 points

Thank you very much !!
it was the capacitance !! really thank you I will not be fired :D

Regards
Camille

0 JMMN over 8 years ago in reply to Camille poumaredes

TI__Guru 60870 points

Glad it works! Let us know if you have any other issues.

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TUSB2046B: Unknown Device