Newnew Technology Corp.

Articles & Case Studies
White Paper

Article
12 Jun 2015

USB 2.0, 3.0, 3.1 Cable Maximum Length Limits


Passive USB Cable length limitations

To meet the signal attenuation and voltage drop budget required by USB specification, for each USB data the maximum cable length varies:

Cable Type Max. Passive Cable Length
USB 2.0 10 m (32.8 ft)
USB 3.0/3.1 Gen 1 5 m (16.4 ft)
USB 3.1 Gen 2 1 m (3.3 ft)

The new USB 3.0 standard has dramatically improved the connection between hosts and peripherals across the world. With its SuperSpeed data transfer rate of 5 Gbit/s and current delivery rates at 900 mA, USB 3.0 has improved upon and supplanted USB 2.0 in numerous applications. Despite these improvements in electrical performance, USB 3.0 is significantly limited by its shorter cable length requirement. In April 2013, an update to the USB-IF compliance for USB 3.0 standards restricted A male to B male cable lengths to three meters maximum. Cables with USB 3.0 Micro B plugs were limited to one meter maximum for compliance requirement. Although these cable lengths are sufficient for typical USB 3.0 connections use at home and/or office, there are many applications in which longer USB 3.0 cables are required.

Breaking the Length Barrier

In response to the growing need for longer USB cables, Newnex Technology Corp. has led innovative efforts to increase USB 3.0 long-distance connectivity.

USB Hub

It is possible to extend the USB connection range with self-powered hubs. The USB cable on either host side or device side of the hub cannot exceed the limits of its standard maximum lengths that are 10m for USB 2.0 and 5m for USB 3.0/3.1. Note, you can only daisy chain maximum 5 hubs in one host-to-device connection. Click to Learn More >>

Active (Repeater) Extension Cables

For applications requiring longer connections, Newnex developed the world's first USB 3.0 active repeater, the FireNEX-uLINK. By restoring attenuated signals that have travelled along cables, this repeater can extend USB 3.0 connections up to 16 meters - 16x the 1-meter length limit. Click to Learn More >>

Optical Fiber Extender

Utilizing similar technology, Newnex also introduced to the world the first USB 3.0 optic fiber extender - FireNEX-5000H. Leveraging the light weight and EMI free advantages of fiber cables, the FireNEX-5000H enables full SuperSpeed data transfer rates at over 300 meters. Click to Learn More >>

An Example Case for USB Extension

USB 3.0 technology has grown popular in major industries such as Machine Vision. An example of a Machine Vision application is when cameras are employed for motion capture. For instance, several of our customers from the golf industry utilized USB 3.0 compatible machine vision cameras equipped with USB 3.0 Micro B connectors to study golf swings by placing cameras around an individual swinging a golf club. Considering an average 0.7 meter arm length along with the fact that the average driver length is 45 inches (~1.14 meters), in order to safely record the individual without limiting his golf swing, cameras should be placed at minimum 2 meters away.

As seen in the figure above, if cameras are placed behind and at the side of the player, the host computer is at least 1.57 meters away from either camera when situated as close as possible while maintaining a 2 meter distance from the player. In addition to these conditions, cameras and computers are usually located at least 1 meter off the ground. At minimum, this creates a cable length of 3.57 meters between computers and cameras without the hazard of suspended cables. Although USB-IF compliance specification requires 1 meter as maximum length for cables with Micro B connectors, cable lengths longer than 1 meter are necessary to ensure safe testing for this particular application. Despite the fact that USB 3.0 provides the sufficient bandwidth and power to aid in this application as well as many other industry applications, longer connections are necessary.


Top