I can't find the purpose of IC ( which is power sourced by VConn) inside the EMCA. Source/Sink can communicate with EMCA via this IC. But what is exactly function of this IC in Power Delivery ?

P/S: IC means : Integrated Circuit inside EMCA( Electronics Mark Cable Assembly - a type of cable which complies with Type-C connector). This IC is powered by Vconn signal.

Thank you!

  • 1
    \$\begingroup\$ Please try to make it easy for people to answer your question by giving some context. Are you talking about a USB-C cable? Which IC? Do you have any links at all? \$\endgroup\$
    – BeB00
    Mar 5, 2018 at 3:56
  • \$\begingroup\$ It would be helpful if you provided some links. \$\endgroup\$
    – BeB00
    Mar 5, 2018 at 4:04
  • \$\begingroup\$ Have you tried searching "Electronically Marked Cable Assemblies" on your favorite search engine? I think you will find some helpful results. \$\endgroup\$
    – uint128_t
    Mar 5, 2018 at 4:06
  • \$\begingroup\$ Oh...I found it, thank you very much for your guidance. I will add the answer for anyone , who need it. \$\endgroup\$
    – son nguyen
    Mar 5, 2018 at 4:12

1 Answer 1


I found the answer for my question: Do all USB Type C cables support full power delivery

In order for a USB-PD compliant source to advertise capabilities greater than 3A (or up to the full 5A limit of the spec) the Type-C cable must be an Electronically Marked Cable Assembly (EMCA) and support SOP' packets. It must respond to the "Discover Identity" VDM sequence (USB-PD spec section with a cable VDO packet with bits 6..5 set to indicate 5A current handling capability.


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