Detailed Technical Analysis of the Lightning Connector
brockerhoff.net/blog/2012/09/23/boom-pins
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
These assumptions also underlie the oft-cited intention of waiting for the $1 cables/adapters. But, recall that Apple specifically said that Lightning is an all-digital, adaptive interface. USB3 is not adaptive, although it can be called digital in that it has two digital signal paths implemented as differential pairs. Remember, the SlimPort designers put a few simple digital signals on the connector and converted them just a cm or so away into another standards differential wire pairs by putting a chip inside the plug.