EZ-USB FX3 Technical Reference Manual, Document Number: 001-76074 Rev. *F 78
6. Universal Serial Bus (USB)
6.1 Introduction
USB is a successful peripheral interconnect defined and heavily adopted in consumer electronics and PC peripherals. The
first version of the specification, USB 1.0, released in 1996, defined two transfer speeds to address the different types of
devices available at that time: 1.5 Mbps (Low Speed) to address devices such as keyboards and joysticks; and 12 Mbps (Full
Speed) to address devices such as disk drives. The USB 2.0 specification, released in 2000, supports a maximum signaling
rate of 480 Mbps (High Speed), which is 40 times the signaling rate of Full Speed. With the introduction of USB OTG, USB
went beyond a peripheral interconnect. It enabled printers to use USB to directly connect to cameras and PDAs to use USB-
connected keyboards and mice. The new generation USB 3.0 is the next revolution in device interconnect technology. It
features the same ease of use and flexibility that users expect, at a much higher (5-Gbps) data rate and advanced power
management.
6.2 Features
The FX3 USB subsystem features the following controllers to support many advanced features of the USB standard:
■ USB Interface Block (UIB)
❐ USB 3.0 function controller
❐ USB 2.0 function controller
❐ USB 2.0 embedded host controller
❐ USB 2.0 OTG controller
■ USB I/O system
❐ Dedicated USB 2.0 OTG PHY and USB 3.0 PHY
❐ Integrated voltage regulator
The USB 3.0 and USB 2.0 subsystems have dedicated transceivers, but they share the same I/O interconnect in the back
end. This means that only one of the USB 3.0 or USB 2.0 controller can be active at a time.
The FX3 USB subsystem supports the following modes of operation:
■ USB 3.0 peripheral in SuperSpeed (5 Gbps)
■ USB 2.0 peripheral in High/Full Speed (480/12 Mbps, respectively)
■ USB 2.0 host in High/Full/Low Speed (480/12/1.5 Mbps respectively), with one downstream port; the hub is not supported
■ USB 2.0 OTG dual-role device (DRD), with Host Negotiation Protocol (HNP) and Session Request Protocol (SRP)
support
6.3 Block Diagram
Figure 6-1 shows the top-level block diagram of the FX3 USB subsystem.
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