USB3.0 Outline of 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 |
Token/Data/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.
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
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 |
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
USB3.0 Standard-A Connector
USB3.0 B Connector
USB3.0 Micro-B Connector
Backward Compatibility
The connector has been modified to maintain connectivity with existing USB devices and cables.
- Technical Overview
- USB1.1 Outline of Specifications
- USB2.0 Outline of Specifications
- USB3.0 Outline of Specifications