USB 3.0 SuperSpeed Technology

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Universal Serial Bus (USB) is the most successful peripheral interface in the history of the personal computer. USB is a standard connection interface between computers and digital devices. It enables the easy transfer of data through a direct connection or cable. USB was created with simplicity of use in mind, and thus “plug-and-play” became the expectation as drivers loaded themselves and printers, external hard drives, and other peripherals “just worked.”

USB has other features that make it attractive for product designs. It provides a small current available to the peripheral, and so USB became a standard for recharging and data transfer in one cable. USB 3.0 ups that current to 900 mA from 500 mA (in 2.0).

The USB 3.0 bus and the USB 2.0 bus operate separately in the same USB 3.0 cable and thus USB 3.0 is backwards compatible with USB 2.0 products by inclusion, with the right cable. SuperSpeed traffic travels in both directions simultaneously, referred to as “full duplex.” The SuperSpeed portion of USB 3.0 hubs do not poll device endpoints to check for ready data; devices operating at SuperSpeed initiate communication with the USB 3.0 hub only when they need it. USB 3.0 also provides for more aggressive power savings modes.

Speed	Low	Full	High	SuperSpeed
Bits per Second	1.5M	12M	480M	4.8G

SuperSpeed now enables streaming video and mass storage at a new level of performance with much faster data transmission rates. Much of USB 3.0 is the same as USB 2.0 from a software standpoint in terms of device classes, data transfer types, and descriptors. Hardware is affected by differential signaling at significantly higher frequencies, however, which can present new challenges to designers in terms of increased signal loss or degraded signal integrity.

Note that USB 3.0 systems cannot utilize both USB 2.0 and 3.0 busses simultaneously; they are mutually exclusive. This holds true with device power consumption as well. Therefore, don’t expect to draw 900mA with a low-, full-, or high-speed USB device. With the largest installed base for interfaces (of USB 2.0) combined with backwards compatibility (of USB 3.0), the new USB is sure to be a winner.

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Click on a category to learn more about USB 3.0.

Host Controller

USB 3.0 Host Controller The USB host controller, often simply referred to as “the USB host,” typically resides in a computer or head-end system. The host controller acts as an interface to move data between the computer and USB bus-resident devices by processing data structures, initiating transactions, and sending the data as packets over the USB bus. It can control several USB ports. Information flow towards the host is called “upstream” traffic and the flow of information away from the host is referred to as “downstream” traffic. The USB specification requires the host controller to include a “root hub,” which provides data flow control for the bus.

» View All Host Controllers for USB 3.0

Hub

USB 3.0 Hub Hubs are the supporting backbone of communication in the USB bus network. A hub in the host controller, called the root hub, provides data flow control at the highest protocol level of the USB network, which is physically nearest to the computer, or head end of the system.

» View All Hubs for USB 3.0

Transceiver (PHY)

USB 3.0 Transceiver A USB transceiver is a physical layer device that prepares data for transmission and then sends to, and receives data from, another transceiver. The transceiver detects connection and provides the low level USB protocol and signaling. The term “transceiver” indicates an implementation of both the transmit and receive functions. It transmits and receives, encodes and decodes data, provides error indication, implements buffers to stage data until it can be managed, and adjusts for the clock rate from the serial stream on the USB SuperSpeed bus to match that of the “link layer” higher up on the communication stack.

» View All Transceivers for USB 3.0

USB to SATA Bridge

USB 3.0 to SATA Bridge This device is used to provide USB 3.0 connectivity to storage devices such as hard disk drives, optical drives and other SATA-dependent devices. It can be used to implement both storage and human interface device class devices for USB. It supports both generation 1 & 2 SATA speeds (1.5 Gbps & 3.0 Gbps, respectively) and includes a Cortex M3 microcontroller. Serial peripheral interface (SPI) and pulse width modulation output are included as well as provision for some general purpose I/O.

» View All USB/SATA Bridges for USB 3.0

Re-driver/Equalizer

USB 3.0 Re-driver/Equalizer USB 3.0 will be targeted initially at the PC market and in devices requiring high rates and volumes of data transfer, such as external storage, consumer electronics, and communications devices with increasing amounts of storage. High frequency signals are subject to problems with signal quality. Signal conditioners can help by filtering out anything above the expected ceiling frequency, and can “re-drive” the signal by retransmitting at increased signal power, effectively “re-driving” it through the signal path. USB is a consumer-friendly technology. Cable lengths for USB devices are not necessarily going to remain fixed at the length of the cable that came in the box. Therefore, the re-driver should continuously monitor the signal and dynamically equalize (or adaptively balance) itself in order to optimize the signal.

» View All Re-drivers/Equalizers for USB 3.0

Plugs/Receptacles

USB 3.0 Plugs/Receptacles USB plugs and receptacles are meant to reduce human error by their unique shape; they fit together in only one way. USB plugs and receptacles come in Type A (typically connecting to hosts or hubs) or Type B (typically connecting to devices) and 3 sizes: standard, mini, and micro. Type A plugs always face upstream, Type B faces downstream.

All USB devices (or peripherals) have an upstream connection to the host and all hosts have a downstream connection to the device. USB 2.0 plugs will fit into USB 3.0 receptacles but do not contain the extra wires needed to convey SuperSpeed communications. Note that USB 3.0 Type B plugs do not fit into USB 2.0 receptacles. A USB 3.0 device going to a USB 2.0 host, for example, will only work with a USB 2.0 cable assembly.

» View All Plugs for USB 3.0

» View All Receptacles for USB 3.0

Cable Assemblies

USB 3.0 Cable Assemblies There is no set standard on cables for USB, but rather for performance of the cable or system. USB 3.0 operates at data rates of up to 5 GHz by employing data-doubling techniques on a 2.5 GHz signal. Higher frequency signals suffer notably more signal losses than lower frequencies, so signal quality can be greatly affected with lower quality cables. To avoid signal degradation, higher-quality thicker-gauge cabling should be used with USB 3.0 devices.

» View All Cable Assemblies for USB 3.0

ESD

USB 3.0 ESD If you have ever been zapped by a socks-wearing kid who has just discovered static charge build up, you have experienced ESD first hand. ESD is like a miniature, localized lightning bolt caused by an electrical discharge. ESD can have seriously damaging effects on an integrated chip or system, or can cause poor performance or failure later on by merely weakening the circuits.

ESD protection should be used where ESD exposure can occur, and is recommended for data cables exposed via their connection points such as USB cable assemblies.

ESD can also be a periodic weak ESD that eventually breaks down the circuit. Devices may escape detection in the factory test harness, but are going to suffer a shorter product life. ESD may occur on any pin that is exposed to its environment. Common mode chokes can also be helpful in reducing, but not eliminating, ESD caused by transmission lines.

» View All ESD Protection for USB 3.0

Chokes

USB 3.0 Chokes Common Mode Chokes are often placed at the base of a USB connector to reduce noise coming from the cable. Common mode choke coils consist of two or more magnetically combined coils that act to isolate unwanted AC frequency currents from a main circuit via two methods: common mode noise rejection and by creating a signal boundary at a defined cut-off frequency. Therefore, chokes can be seen as signal conditioners of a kind. Note that chokes are not full ESD (electrostatic discharge) protection devices, but can help reduce aspects of ESD system upset in addition to their main function of general noise reduction.

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» View All Chokes for USB 3.0

Switches

USB 3.0 Switches provide smooth transitions. By maintaining low resistance and impedance, the signal switch can keep insertion losses down and preserve the signal so that no glitches are reflected back to the transmitter, thus helping to maintain a good quality signal.

» View All Power Switches for USB 3.0

» View All Signal Switches for USB 3.0

Clocks

USB 3.0 Clocks USB 3.0 requires a Clock. Clock technology is more expensive and more complicated at higher frequencies. A lower frequency clock can be used and then multiplied to achieve the desired clock rate; however any jitter (error) is also multiplied. (Jitter is shakiness in the signal, caused by electro-magnetic radiation or the influence of nearby signals.) Circuitry supporting clock function should be selected for low noise.