Insight - How USB Connector Works

Just like their name, Universal Serial Bus connectors, are unanimously used as a carrier in power and data exchange operations. Developed and promoted by computing giants like Intel, Microsoft, Dell, IBM and NEC, USB interfacing has been highly preferred to connect various computer peripherals. Mouse, keyboard, cameras, printers, scanners, laptop cooling pad, external memory are the prominent few names among a long and increasing list. Apart from computers, USB based connectors have also arrived in television, mobile phone chargers, multimedia players etc.

USB connectors are of various types depending on the number of pins, shape, application etc. This article would detail in a standard “A” type USB connector which has 4 pins that serve for power as well as data exchange purposes. Let’s find out how the internal structure of this connector manages to make its use simple and thus, popular.

Fig. 1: Top View of A-type USB Connector

Metal Casing

Metal Casing

The image above shows the top view of A type USB connector. The metallic box provides durability and ensures protection from mechanical stresses. Two cut sections are made to establish a firm connection for latching with the female counterpart. Output pins are seen from the rear part of the connector.

Fig. 2: Pin Layout in Male Side of Connector

A rectangular opening in the front of the male connector is there from which the female connector is linked to it.

Pin out Diagram: Beneath the metal casing resides the internal pin structure. The pin out diagram of a standard A type USB connector is:

Pin 1: Voltage (+5V)

· Pin2: Data (+)

· Pin3: Data (-)

· Pin4: Ground.

Wires connected to the pin outs are color coded in the following manner:

· Voltage: Red color

· Data +: Green color

· Data -: White color

· Ground: Black

USB connector based interfaces are susceptible to noise and hence the signal is sent in a differential form through data+ and data- pins.

Fig. 3: Layout of Pins in Plastic Insulating Base

Placement of Pins

Connector pins are laid on a plastic insulating base. The length of voltage and ground pin is more than the data pins. The reason for this is to provide an established connection before any data exchange takes place otherwise; there might be incorrect data reads or damage of the device connected due to voltage fluctuations.

This is the reason why USB device need to be closed down through software before they are physically disconnected from a computer. When taken out without without closing them properly, user might disrupt data transfer that further results in data corruption or might give a sudden power blackout to the USB connected interface.

Fig. 4: Image Indicating the Bulge of USB Connector Pin

Structure of Pins

A USB connector pin is straight and has a bulge that allows a firm connection with the female USB connector.

Fig. 5: USB Pin Structure and Parts

This is how a conventional USB pins looks. The front part interfaces with the female connector. Wires are soldered at the rear part of USB pin to carry the data to the device.