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When to Use USB 1.1 vs. 2.0 vs. 3.0

USB is a standard that was developed in the mid-1990s that defines cables, connectors and communication protocols. This technology is designed to allow a connection, communication and power supply for peripheral devices and computers. USB ports are dynamic in the amount of devices that are supported. In theory, a single USB port is capable of supporting up to 127 devices through the use of USB hubs. USB devices can range from human interface devices, i.e. keyboard, mouse, etc., to storage devices, i.e. thumb drives, external hard drives, etc.

The USB 1.1, or Full–Bandwidth USB, specification was the first release to be widely adopted by the consumer market. This specification allowed for a maximum bandwidth of 12Mbps. This type of USB connection is ideal for connecting devices that have low bandwidth requirements, i.e. keyboard, mouse, printer, etc.

The USB 2.0, or Hi–Speed USB, specification made many improvements over USB 1.1. The main improvement was an increase in bandwidth to a maximum of 480Mbps. This specification retained a backwards compatibility which allows USB 2.0 controller cards to support USB 1.1 devices. USB 1.1 devices used on a USB 2.0 controller card do not benefit from the additional bandwidth provided and will be limited to a maximum bandwidth of 12Mbps. The additional bandwidth provided by the USB 2.0 specification is best suited for supporting devices requiring the high bandwidth, i.e. mass storage devices, video adapters, data transfer cables, etc.

The USB 3.0, or SuperSpeed, specification made further improvements to USB technology. The primary improvements include an increase of bandwidth to a maximum of 4.8Gbps, support for full duplex communication and an increase of the amount of power available to connected devices. This specification retained a backwards compatibility that allows USB 3.0 controller cards to support USB 2.0 and USB 1.1 devices. USB 1.1 and USB 2.0 devices used on a USB 3.0 controller card do not benefit from the additional bandwidth provided and will be limited to USB 1.1 and USB 2.0 maximum bandwidths respectively. The additional bandwidth, full duplex communication and power availability provided by the USB 3.0 specification is best suited for supporting devices requiring high bandwidth, i.e. large mass storage devices, video adapters, data transfer cables, etc.

USB Specification Maximum Bandwidth Power Supplied Typical Application
USB 1.1 Full–Speed 12Mbps 100mA for unconfigured devices, 500mA for configured devices Low bandwidth devices, i.e. keyboard, mouse, printer, etc.
USB 2.0 Hi–Speed 480Mbps 100mA for unconfigured devices, 500mA for configured devices High bandwidth devices, i.e. mass storage devices, video adapters, transfer cables, etc.
USB 3.0 SuperSpeed 4.8Gbps 150mA for unconfigured devices, 900–1000mA for configured devices High bandwidth devices, i.e. large mass storage devices, video adapters, transfer cables, etc.

This white paper is for informational purposes only and is subject to change without notice. C2G makes no guarantees, either expressed or implied, concerning the accuracy, completeness or reliability of the information found in this document.