Universal Serial Bus Connectors
Types of USB Connectors
Currently, there are four types of
USB connectors: Type A, Type B, mini-A and mini-B and are supported by
the different USB specifications (USB 1, USB 2 and USB-OTG).
Type A (Host)
Often referred to as the downstream
connector, the Type A USB connector is rectangular in shape and is the
one you use to plug into the CPU or USB hub.
Type B (Device)
Also called the upstream connector, the
Type B USB connector is more box-shaped and is the end that attaches
directly to the device (such as a printer or digital camera).
USB 1.1 specifies the Type A and Type B.
The USB 2.0 connector was too large for many of
the new handheld devices, such as PDAs and cell phones. The mini-B was
introduced to enable consumers to take advantage of USB PC connectivity
for these smaller devices.
USB 2.0 specifies the Type A, Type B and mini-B.
With the need to connect mobile devices without
the aid of a computer, the mini-A port was designed to connect the new
generation of smaller mobile devices.
USB OTG specifies the mini-A.
First released in 1996, the original USB 1.0
standard offered data rates of 1.5 Mbps. The USB 1.1 standard followed
with two data rates: 12 Mbps for devices such as disk drives that need
high-speed throughput and 1.5 Mbps for devices such as joysticks that
need much less bandwidth.
In 2002 a newer specification USB 2.0, also
called Hi-Speed USB 2.0, was introduced. It increased the data transfer
rate for PC to USB device to 480 Mbps, which is 40 times faster than
the USB 1.1 specification. With the increased bandwidth, high
throughput peripherals such as digital cameras, CD burners and video
equipment could now be connected with USB. It also allowed for multiple
high-speed devices to run simultaneously. Another important feature of
USB 2.0 is that it supports Windows XP through Windows update.
|Different types of USB connectors from left to right
♦ Mini-A plug
♦ Mini-B plug
♦ B-type plug
♦ A-type receptacle
♦ A-type plug
|Pin configuration of the USB connectors Standard A/B,
viewed from face of plug
|1 ||VCC||Red ||+5V |
|2 ||D- ||White||Data -|
|3 ||D+ ||Green||Data +|