USB or Universal Serial Bus connectors are one of the most common interfaces used in connecting peripherals to computers. First USB was developed as an industry standard in mid 1990`s by the coalition of vendor companies Compaq, DEC, IBM, Intel, Microsoft, NEC, and Nortel.
The standard defines cables, connectors, and communications protocols when connecting a device to a computer. It can play multiple roles; it acts as a bus in connection to computers for data communications between computer and devices. It can also be used as a power supply to a device.
Three versions of the USB standard have been released up to now. USB1 was released in January 1996, known as Full Speed version; have speeds of 1.5 Mbit/s (Low-Bandwidth) and 12 Mbit/s (Full-Bandwidth). USB 2.0 was released in 2000 (known as High Speed version), where higher data transfer rates and many more features were introduced. USB became very popular after this release.
The latest version of USB standard, which is USB 3.0 (known as Super Speed version), was released in November 2008, and the data transfer rate have been further upgraded in this release. Among many connector types developed for the USB standard USB mini and USB micro are two types used frequently in smaller devices such as mini computers, portable and mobile devices.
Mini USB
Two types of mini USB connectors were developed; namely, USB mini A and USB mini B. These connectors are 3 x 7 mm in size and are often used in mobile devices such as camcorders. There is an extra pin compared to the standard USB connector, know as ID pin, which was introduced for further development of the standard.
These were introduced in the USB 2.0 version, but now considered as legacy. Mini A connectors are de-certified and mini B connectors are still supported by the standard without the On the Go capability.
Micro USB
Micro USB was introduced in May 2007. Micro USB also has two variations as A and B, and they have dimensions 6.85 x 1.8 mm, which is almost the same width of the mini connectors, but half the thickness. Micro USB is the accepted standard for the mobile devices now. Micro USB is supported by OTG (On the Go), which allows a device to be connected as a slave device at a time and master device at another time. This capability was an addition to USB 2.0 standard to facilitate intelligent devices such as PDA`s and smart phones to connect to other peripherals such as printers, without a computer.
The connector is designed for rough use and can tolerate 10000 connect-disconnect cycles. The ID pin is available in micro USB AB connectors too, but unlike the mini version they have a function; the ID pin allows the device to function either as A or as B connector with the standard USB technology.
Micro USB vs Mini USB
• Mini USB was the earlier standard for the USB used in mobile devices, now deprecated. Micro USB, an addition to USB version 2.0 in 2007, is now the standard connector type for mobile devices.
• Mini USB is less durable than the micro USB where micro USB can operate for 10000 connect-disconnect cycles.
• Micro USB connectors are smaller; they are almost of the same length and half the thickness of the mini USB.
• ID pin in mini USB is idle, whereas ID pin in micro USB can be used to allow the connector used in both A and B type receptacles.