What is the difference between micro-A and micro-B USB?

08 Apr.,2024

 

USB connectors come in different sizes and types. Not all size and type combinations are valid, and only a few of them are used in majority of applications.

USB is asymmetrical: there's a host (originally a computer) and a peripheral device (flash drive, mouse, mobile phone etc.) The original type A/type B dichotomy reflects this asymmetry: type A was intended for hosts and type B for peripherals. Full-size type A is the most common, large rectangular connector with a horizontal plastic tab taking half of the slot. Full-size type B is the square-ish connector with two truncated corners, nowadays used mostly to connect printers.

Then there's the mini size, which was created to be used in devices too thin to fit a full-size connector. Mini type B was used for some time, superseded by even smaller micro type B which is still very common in mobile phones and various devices that charge from USB. Mini type A exists, but is practically unheard of. There's also mini type AB and micro type AB, but I've never seen one of these.

Most recently, the type C connector was introduced. Its original form factor is small enough to replace micro type B. It's also reversible, which is awesome. Type C can be used both for hosts and peripherals.

So the most common USB types are:

  • USB type A - usually called simply "USB"
  • USB type B - "that printer cable"
  • Micro USB type B - "micro USB"
  • USB type C

"Micro B" on the image you've posted is just an unofficial, shorter way of writing "micro USB type B". "Micro-USB" is the same thing.

Known as "SuperSpeed", this A-style connector is commonly found on host controllers in computers and hubs, the A-style connector is a flat, rectangular interface. This interface holds the connection in place by friction which makes it very easy for users to connect and disconnect. Instead of round pins, the connector uses flat contacts which can withstand continuous attachment and removal very well. The A-socket connector provides a "downstream" connection that is intended for use solely on host controllers and hubs. This connector is similar in size and shape to the A-Type connector used in USB 2.0 & USB 1.1 applications. However, the USB 3.0 A-type has additional pins that are not found in the USB 2.0 & USB 1.1 A-Type. The USB 3.0 connector is designed for USB SuperSpeed applications; however, it will carry data from slower speed connections, and it is backwards compatible with USB 2.0 ports. USB 3.0 A connectors are often blue in color to help identify them from previous versions.

What is the difference between micro-A and micro-B USB?

What Is USB? USB, Micro and Mini USB