USB Theory: USB Specifications
There are three different types of USB specifications widely used in the world today. They are all backward compatible with previous revisions, while adding more features and functionality to the existing data bus. The primary difference that the end-user will notice between revisions is data transfer rates are significantly increased, which means less time to save stuff!
Standard USB Guidelines
USB 1.1 - September 1998
USB 2.0 - April 2000
****This Tutorial Designs For USB 2.0****
USB 3.0 - November 2008
There are three different types of USB specifications widely used in the world today. They are all backward compatible with previous revisions, while adding more features and functionality to the existing data bus. The primary difference that the end-user will notice between revisions is data transfer rates are significantly increased, which means less time to save stuff!
- Connector: 4 Pin (PWR/D+/D-/GND); USB 3.0 - 9pins
- Power: +5v (no less than 4.75v)
- Cable Length: 3-5 meter (shorter is better)
- Cabling: Use Twisted Pair Wiring and Shielding
- PCB Layout: 90Ω Characteristic impedance, 45Ω Terminations
- Data: D+/D- differential data lines
- Low-speed: 1.5 Mbit/s - (183 kB/s) ~> From USB 1.0
- Full-speed: 12 Mbit/s - (1.43 MB/s)
- 500mA max current draw per USB channel
- Only 1 Connector - Type A
- High-speed: 480 Mbit/s - (57 MB/s)
- 500mA max current draw per USB channel
- Connector Types B, C & Mini USB Introduced
- Super-speed: 4800 Mbit/s - (572 MB/s)
- 900mA max current draw per USB channel
- CRC-16/CRC-32 For Header/Payload Protection
- 9 pin Connector Introduced