L509, L1,L2 - what's the P/N? Is it needed?

Couldn’t find those 3 inductors in the BOM file.

Are they needed? or that they are leftover from first days?


Hi, they are not mounted and bypassed with resistors. If you want to use common-mode choke, please check the Table USB 3.1 Interface Signal Routing Requirements in OEM DG for the requests of it and so choose in market accordingly.


Table 21 has no information on the reason for the Common-Mode-Choke (CMC), so I looked and found a discussion on this, and my understanding is that it is required only when EMI is an issue.

Here’s the link to the discussion, which provides link to Intel’s documents on USB design.


High Speed USB Platform Design Guidelines

Intel EMI Design Guidelines for USB Components