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The USB Type-C Cable and Connector Specification specifies (section 3.5) that in legacy cable assemblies (cables that have an non type-C plug on one end) the CC pin of the C plug (pin A5) must be connected to Vbus through a 56k or to GND through a 5.1k resistor (Note 1 in the images below), depending on the specific cable.

However, all legacy assemblies, except for mini-B (second image), also list the Vconn pin of the C plug (pin B5) in the wiring table. Yet pin B5 is not mentioned in Note 1, and no connection is specified.

Does pin B5 need to be connected to Vbus/GND through a resistor as well? Or to anything else? If not, why is this pin listed in the cable wiring table? After all, the last note already specifies that any pin that is not in the table is not connected. And why is mini-B the only cable where it is not listed?

I know what the function of Vconn is in an active C-to-C cable, my question is specifically about the specification of the legacy cables.

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1 Answer 1

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The cables are passive, not active or E-marked, so it has no use for Vconn.

So it does not need to connect it in any way and can be left open.

The host will correctly detect one pin having 5k1 to ground on your device through cable, and one pin open.

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