USB3.0 Cable Physical Analysis

USB 3.0 cable physical analysis

The most common PC peripheral interface in daily life is USB. 8 years ago, USB 2.0 (USB Hi-Speed) greatly increased the transmission speed of USB interface from 12Mbps to 480Mbps. Now, Intel is leading a group of industry manufacturers to develop the next generation USB 3.0 standard, also known as USB Superspeed, which is expected to increase the speed by 10 times again. If nothing unexpected happens, USB 3.0 will soon become the universal interface standard in the PC industry. As an enthusiast, you must know it. The following is a summary of the "Usage Instructions" of the USB 3.0 standard for you, corresponding to the actual cable:

USB 3.0 cable

Backward compatibility

Just like the upgrade from USB 1.1 to USB 2.0, the physical characteristics of the new USB 3.0 interface and cable are backward compatible. Of course, as long as one of the devices, interfaces and wires does not support the USB 3.0 standard, Superspeed cannot be achieved, but at least you can rest assured that the USB 3.0 cable will not explode when plugged into a 2.0 interface. The key to compatibility lies in the interface design of USB 3.0. The USB 2.0 interface has a total of 4 lines, two of which correspond to data input and output, and the other two are power supply and ground. USB 3.0 adds 5 contacts on this basis, and the new contacts are located side by side behind the 4 USB 2.0 contacts. In other words, you can see the difference between 3.0 and 2.0 cables from the USB connector.

The five new contacts are faintly visible on the back of the USB 3.0 port.

Top speed

The maximum transfer speed of USB 3.0 is 4.8Gbps, 10 times faster than the 480Mbps of USB 2.0. According to Intel, a 27GB high-definition movie can be transferred in 70 seconds using USB 3.0, while it would take more than 15 minutes using USB 2.0. Of course, such speed requires the support of storage devices. Future solid-state drives may benefit from the high bandwidth of USB 3.0, while traditional hard drives may not be able to keep up with the speed of USB 3.0. In addition, Windows systems must also install a new Mass Storage Device driver to support the new USB standard.

Bidirectional transmission

The input and output lines of USB 2.0 cannot work at the same time, that is, the output cannot be achieved when the signal is input. Among the 5 lines added by USB 3.0, two are for data output and two are for data input, and these four lines can achieve bidirectional transmission at the same time. Such a bidirectional transmission mode will greatly increase the speed when synchronizing information or backing up data on a mobile phone.

USB 3.0 not only has a higher speed, but also can provide stronger power. There are a large number of digital products on the market today that need to be charged through the USB interface, so the developers have improved the power supply capacity of USB 3.0 from 100mA to about 900mA. This means that USB3.0 mobile hard drives will rarely use additional power supply, and passive USB-Hubs can also connect more devices.

Mini USB 3.0 port for mobile phones or other mobile devices

High energy efficiency

USB 3.0 introduces a more energy-efficient power supply protocol standard, abandons the device polling mode, and adopts the interrupt mode instead. In layman's terms, in USB 2.0 mode, even if the connected USB is in inactive or standby mode, the USB bus controller still needs to periodically check whether the device needs to transfer data. In USB 3.0 mode, the device can completely cut off the USB connection when it is in standby mode, and when it needs to be restored, it will automatically send an interrupt signal to the controller to inform the controller to start data transmission. Of course, USB 3.0 is still backward compatible with USB 2.0 mode.