TUSB8041: Configuration of the HU IC and HD3SS3220 as DFP

Juan Jose Frutos Andreu

Part Number: TUSB8041
Other Parts Discussed in Thread: HD3SS3220

Hi,

I am designing a system which is composed of a USB 3.0 HUB device (TUSB8041), two on-board USB3.0 devices and two DFP USB3.0 devices, making the USB3 to C conversion using the HD3SS3220 as DFP.

I have a simple question.

There are two HUB ports that are conected to the on-board USB3.0 devices, this connection will need on de USB series 100nF cap in both TX lines, I men on TX HUB side and on TX device side, is this correct?

On the other hand, the two HUB ports are connected to the HD3SS3220 in order to make the type C conversion, thesee ports are not required of this 100nF caps right?

Also the Host connection of the USB HUB is made via USB type C, so an other HD3SS3220 will be placed there, again, I think that no 100nF caps are needed. Please Confirm my assumtions are right.

Please find attached the schematic pages of the HD3SS3220 as DFP configuration, the HD3SS3220 as UFP (HOST_PAGE) and the TUSB8041 configuration. Can you confirm that the ICs are properly configured?

On both systems we are using GPIO configuration, and in the HUB overcurrent or battery charging charasteristics are not anabled.

Best Regards,

2330.HUB.pdf DFP.pdf UFP.pdf

over 7 years ago

0 Malik Barton57 over 7 years ago

TI__Guru 64326 points

Juan,

The configuration of the TUSB8041 and HD3SS3220 seem correct. To answer your questions:

1) Yes 100nF cap are needed on both Hub and on-board USB3.0 devices TX lines.
2) No, the two HUB ports that are connected to HD3SS3220 must be have these 100 nF on both TUSB8041 andHD3SS3220 TX sides .

0 Juan Jose Frutos Andreu over 7 years ago in reply to Malik Barton57

Intellectual 610 points

Hi Malik,

Thanks for the quick response.

I am having a look at the Figure10 of the HD3SS3220 datasheet (page 24). In figure 10 I see that there are no 100nF caps on any data lines.

¿Can you please confirm that the 100nF caps are needed? We have already a design with the HD3SS3220 as UFP, we dind't place the caps and it works fine. Or the caps are needed due to the HUB?

There must be also the 100nF caps on the Host side of the HUB?

Best Regards,

Thanks,

Juanjo

0 Malik Barton57 over 7 years ago in reply to Juan Jose Frutos Andreu

TI__Guru 64326 points

Juanjo,

Yes the 100 nF are needed between the TUSB8041 and HD3SS3220. These capacitors are used on each devices transmitter as stated in the USB spec (see image below). This would also apply to the Host side of the HUB.

It is possible that you have enough capacitance on the TX lines between the two devices to meet the lower end of this spec however I would still recommend placing the 100 nF capacitors.

0 Juan Jose Frutos Andreu over 7 years ago in reply to Malik Barton57

Intellectual 610 points

Thanks Malik.

0 Juan Jose Frutos Andreu over 7 years ago in reply to Malik Barton57

Intellectual 610 points

I am Sorry Malik I have to ask.

Then why on all the HD3SS3220 application schemes are not shown this 100nF caps.

Regards,

0 Juan Jose Frutos Andreu over 7 years ago in reply to Juan Jose Frutos Andreu

Intellectual 610 points

Mi Malik,

Please find the following link of the TI support forum where your college told me that they were not necessary (the nearly last response)
e2e.ti.com/.../633029

I would like to know how to procced with theese caps.

Regards,

Juanjo

0 Malik Barton57 over 7 years ago in reply to Juan Jose Frutos Andreu

TI__Guru 64326 points

Juanjo,

I apologize, I was incorrect in my earlier post. For HD3SS3220 you only need AC coupling caps on one side of the switch. So it is okay to not have AC caps between the TUSB8041 and HD3SS3220.

0 Juan Jose Frutos Andreu over 7 years ago in reply to Malik Barton57

Intellectual 610 points

Hi Malik,

Thank you so much.

Best Regards,

Juanjo

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TUSB8041: Configuration of the HU IC and HD3SS3220 as DFP