TUSB2046b hub cascading

Quenton Hall

Other Parts Discussed in Thread: TUSB2046B

Hi folks,

We are cascading 3 TUSB2046B hub chips to make a 10-port hub. Our question is regarding the connection of the upstream port of one hub to the downstream port of another. It looks like we need a a 22pF cap to ground, a 22R series resistor, and a 15k pulldown on DM and DP. It also appears that we need a 1.5K pullup to 3.3V on the DP0 input. Our understanding is that these requirements will apply to each of the cascaded hubs, whether the ports are external or cascaded.

Can TI confirm that our understanding is correct?

Kind regards,

Quenton

over 12 years ago

0 Elias Villegas M. over 12 years ago

TI__Guru* 76130 points

Hello,

Your understanding is correct, you need all the passive components between tiers.

Regards.

0 Quenton Hall over 12 years ago in reply to Elias Villegas M.

Prodigy 135 points

Hi Elias,

Thanks for your help with this. If possible, I would like to send you a private message with a copy of our customer's schematics so that you could do a quick review. Please let me know if this would be possible.

Kind regards,

Quenton

0 Quenton Hall over 12 years ago in reply to Elias Villegas M.

Prodigy 135 points

Hi Elias,

What references would you recommend for customers who are asking for layout guidelines for this part?

Kind regards, Quenton

0 Elias Villegas M. over 12 years ago in reply to Quenton Hall

TI__Guru* 76130 points

I would recommend the below doc.

http://www.ti.com/lit/an/spraar7a/spraar7a.pdf

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TUSB2046b hub cascading