Why does STM32MP257F-DK not having EMI-filters on RX lines for USB 3.0?

[Windows]

Why does STM32MP257F-DK not having EMI-filters on RX lines for USB 3.0?

Can it be like a common standard that the transmitter TX should always have:

• AC capacitors
• ESD protection
• EMI-filtering

And the RX does not need anything of those, because it’s assuming that their transmitter already having these implemented?

This picture is from mb1605-mp257f-c01-schematic.pdf

 

[FBL]

Hi ​@Windows 

Checking USB3 standard in  USB 3.2 Revision 1.1 - June 2022 | USB-IF, section 6.8.3 Receiver Electrical Parameters

Table 6-22

On RX, it seems optional.

[Windows]

​@FBL 

 

Thank you so much. Yes, the RX lines are optional for AC capacitors.

But why did ST not implement EMI filter for RX lines as well?  Just wondering. 

[PatrickF]

Hi ​@Windows 

 

Probably multiple explanations (guess):

• There is no product related emission on RX lines, so no need of EMI filter to fulfill product standards (FCC or similar).
• There is already ESD protection inside FUSB340 switch RX
• The serie capacitor on TX might need to be protected from ESD (I’m not sure about that)

 

Regards.