Hardware Reference
In-Depth Information
Forbackwardcompatibility,USB3.0hubsalsoincludeaUSB2.0hub,allowingoperation
in both USB 3.0 and 1.1/2.0 modes at the same time. USB 3.0 also operates using switch-
ing,wherecommunicationisdonebetweenthehostandeachdeviceindependently,rather
than being broadcast to all devices. This is far more efficient than the broadcasting tech-
niqueusedbyUSB2.0andprior.DevicesthatpassUSB3.0compliancetestingmaycarry
the SuperSpeed USB certified logo shown in
Figure 14.9
.
Figure 14.9
SuperSpeed certified USB logo.
USB 3.0 connectors and cables have an additional five pins dedicated to the SuperSpeed
function (two SuperSpeed differential signal pairs plus a ground), whereas the four exist-
ing USB 1.1/2.0 pins remain for full backward compatibility. The socket has the new pins
mounted just above and in front of the existing pins. USB 3.0 sockets accept both USB
3.0 plugs and cables and USB 1.1/2.0 plugs and cables.
Figure 14.10
shows the USB 3.0
socket design.
Figure 14.10
USB 3.0 sockets for circuit board mounting.
