Basic Specifications

USB 3.0 adds a new transfer mode, SS (SuperSpeed), which provides a maximum transfer rate of 5 Gbps, more than 10 times faster than the existing HS (high-Speed) mode. USB 3.0 thus aims to support application media requiring fast and high-capacity transfers.

SS uses an independent pair of wires for IN and OUT. The faster transfer rate for SS mode is achieved by using a bus configuration different from previous USB specifications.

USB3.0 vs USB2.0

Features USB3.0 USB2.0
Data Rate SuperSpeed (5.0Gbps) additional low-Speed (1.5Mbps)
full-Speed (12Mbps)
high-Speed (480Mbps)
Data Signal
  • SS OUT Differential Signal: 1 Pair
  • SS IN Differential Signal: 1 Pair additional
Differential Signal: 1 Pair
Connector Signals
  • 4 wires: SuperSpeed
  • 2 wires: DP/DM for USB 2.0
  • 3 wires: Vbus/GNDx2
2 wires: DP/DM for USB 2.0 2 wires: Vbus/GND
Bus Protocol No polling Uses polling
Power Control Configuration at multiple link levels Suspend/Resume by Port
Power Supply to Bus Max. 900 mA Max. 500 mA

Characteristics of SuperSpeed Transfers

Characteristic SS HS/FS/LS
Bus Configuration Dual Simplex Unicast Bus Broadcast Half Duplex Bus
Transaction Configuration
  • Data/Handshake
  • OUT Token is included in Data Packet
  • IN Token is replaced by Handshake
Burst Transfer Supported Unsupported
Start Token Asynchronous Notification by Device Polling by Host

Power Supplying Capability

USB 3.0 also offers enhanced bus power.

USB can now carry a current of up to 900 mA/port, up from the previous 500 mA/port, providing a more stable power supply to the devices.

Power Supplying Capability

Behind the Higher Transfer Rate

In recent years, the amount of information that is handled by products equipped with USB has increased. There has also been a progression in the speed and size of media formats. For this reason, as a new interface standard, the market has been buzzing with excitement over USB 3.0 that offers data transfer 10 times faster than existing products.

For example, it proves its stress free usability in the case of downloading a 25GB HD video. While USB 2.0 would take 14 minutes, USB 3.0 only takes 70 seconds.

Data Transfer with USB 3.0

Data Transfer with USB 3.0

Growing demand for faster data transfer

  • " Larger data " HD videos: 4.7 GB (DVD-R) → 25 GB (BD-R)
  • " Larger media ": HDD (500 GB), HD-DVD (15 GB)
  • " Faster media " Flash ROM based products (SSD, HHD, etc.)

Comparison of Data Transfer Rate

USB version (Data Transfer Rate) (Throughput)

USB1.0 (12Mbps) (1MB/s)

USB2.0 (480Mbps) (30MB/s)

USB3.0 (5Gbps) (over 300MB/s)

Media (Data Size) Transfer Time
Song / Pic (4 MB) 5.3 sec 0.1 sec 0.01 sec
256 Flash (256 MB) 5.7 min 8.5 sec 0.8 sec
USB Flash (1 GB) 22 min 33 sec 3.3 sec
SD-Movie (6 GB) 2.2 hr 3.3 min 20 sec
USB Flash (16 GB) 5.9 hr 8.9 min 53.3 sec
HD-Movie (25GB) 9.3 hr 13.9 min 70 sec

Backward Compatibility

  • Like its predecessor, USB 3.0 will offer backward compatibility.
  • USB 3.0 cables are now 9-wired, instead of the previous 4, and have modified connectors.
  • Dimensions remain the same. USB 3.0 functionalities are provided when the added signal lines become connected.
USB 3.0 Connector

USB 3.0 connector

USB3.0 Standard-A Connector

USB 3.0 Standard-A Connector

USB3.0 B Connector

USB 3.0 B Connector

USB3.0 Micro-B Connector

USB 3.0 Micro-B Connector

Backward Compatibility

The connector has been modified to maintain connectivity with existing USB devices and cables.

Backward Compatibility Diagram

Learn more