Everything You Need to Know About USB Connectorsoriginal_584694571

In 1994, a group of seven tech companies began the development of the universal serial bus, or USB. The group, comprised of Compaq, DEC, IBM, Intel, Microsoft, NEC, and Nortel, sought to improve upon how machines spoke to each other by reducing the amount of parallel and serial ports that computers were using.

The electronics industry took a few years to adopt USB interface, however now you can readily find USB technology everywhere.

This outline on USB will look at the following:

USB’s Background

Standards for USB

USB Connectors & Ports

The Future of USB


USB’s Background

Before USB - text and imageBefore USBs, there were a lot of compatibility issues among the various ports and devices users would try to use. Devices, or peripherals, are any external elements you connect to the main machine, such as mice, printers, keyboards, etc. Before USB, users would often have to reboot the computer system to connect a peripheral. And some ports could not even run multiple devices simultaneously. There was clearly a need for better technology.

USB is now arguably the most recognizable connector. The speed in which USB operates, coupled with the ability to power devices is one of the many reasons why this connector has become as popular as it is.

USB operates as a plug and play device, where you connect one end to the Host (computer) and the other end to the peripheral device (keyboard, phone, camera, etc.). You are unable to connect two peripheral devices together without a host. USB is only able to handle one host per bus.

USBs have been with us for over 2 decades and are continually updated for speed and performance to keep up with advances in technology with heavier data requirements, slimmer devices, and consumer streaming needs.

USB Generations released:

  • 1996, USB 1.0 released with a transfer rate of 12MBps (megabit per second), Low-Speed
  • 1998, USB 1.1 released with a transfer rate of 12MBps, Full-Speed
  • 2000, USB 2.0 released with a transfer rate of 480MBps, Hi-Speed
  • 2008, USB 3.0 released with a transfer rate of 5Gbit/s (gigabit per second), SuperSpeed
  • 2013, USB 3.1 released with transfer rate of 10Gbit/s, SuperSpeed
  • 2017, USB 3.2 released with transfer rate of 20Gbit/s, SuperSpeed+

USB Standards

USB standards are set forth by the USB Implementers Forum, Inc. (USB-IF). This is a non-profit corporation that is composed of industry representatives that include Apple, HP Inc., Intel, Microsoft, Texas Instruments, and more.

USB-IF is a support organization that encourages USB advancement and industry adoption. The form issues trademark-protected logos for products that pass their compliance testing. This helps consumers feel secure in selecting USB products and helps advance the technology.

Among the forum’s activities, they cite on their website that they provide the following:

  • USB Compliance Workshops
  • USB compliance test development
  • www.usb.org Web site
  • USB communities at Computex and other events
  • Marketing programs and collateral materials, such as retail newsletters, retail salespeople training, store end-caps, etc.
  • USB Developer Conferences
  • and many more... 

USB Connectors & Ports

As noted earlier, USB has released three versions: USB 1.0, USB 2.0, and USB 3.0, with several iterations of those versions.

There are 7 types of USB connectors:

Type A:

This is the standard, flat, rectangular shaped connector that is most commonly used and recognized. All computers have USB A sockets. It is the 4-position connector as described earlier.

USB Type A Full View                           USB Type A Front View

View USB-A Connectors



 This is a square shaped USB connector, that is primarily used for devices such as printers or older cameras. It is not as common these days due to modern devices moving to a smaller connection. It is also a 4-position connector with the same pin outs.

USB Type B Front View

View USB-B Connectors


Mini A and Mini B

These are variations of the Type A and Type B where connector size is significantly smaller. These mini versions are used on smaller devices to conserve space, such as portable cameras, cell phones, and video game controllers. It has 5 positions, where the 5th pin is used as a device indicator.


View Mini-USB Connectors


Micro A and Micro B

The Micro USB’s are another step forward in minimizing space used in devices. You will commonly see these sockets on Tablets, smartphones, and video game controllers. The Micro and Mini Series are slowly being phased out and moving on to Type-C.

USB Micro AB

View Micro-USB Connectors



USB Type C is the newest USB standard that is becoming increasingly popular and favored. This is a reversible connector which means it can be plugged in in either orientation. It has high transfer rates and can handle multiple functions due to its 24 pins (Power, video, audio, and data capability).


View USB-C Connectors


Similarities and Differences

There are 4 shielded wires to a USB type A. They are labeled as +5V, Data-, Data+, and a ground (GND).

Power is used through the two wires +5v and GND. The other two remaining pins are used for carrying differential data signals. They are transmitted on a twisted pair. Their half-duplex signaling (transmitting signals in both directions, but not simultaneously) is used to combat electromagnetic interference which can disrupt communication.

Through the years the data transfer speed has increased significantly with higher power levels following as well. The only way to know the difference between USB 3.0 and USB 1.0 is by color. While the outside shell and shape is the same, the plastic inside the device will be blue for USB 3.0, black for USB 2.0, and white for USB 1.0.

  • USB 1.0 has the slowest data rate, and due to its lower power limits and timings it is not able to be used as an extension cable or a pass through for monitors. USB 1.1 is the first revision of the 1.0 series, with its upgrade being data transfer speed. With this increased speed we begin to see personal computers (PC) come equipped with these sockets. 1.1 has limitations such as a max cable length of 5 meters.
  • USB 2.0 is an upgrade from USB 1.0 where its biggest improvements is in the data transfer speed. It still supports a max length of 5 meters.
  • USB 3.0 supports a drastically faster data transfer speed and does not have a specific cable length for operating. However, USB 3.0 cables do need to meet certain electrical specifications such as 3-meter length for copper cabling with AWG 26 wires.

It’s important to note that all USB types can be offered in USB 1,2, and 3. USB type is the connector shape, the technology in the connector can be any USB.

Out of the 7 USB types out in the market, Type-C is the most favorable. It is roughly the same size as a micro USB connector, but offers speeds like USB 3.1. Due to its capabilities in transmitting audio it is now seen as a potential replacement for the 3.5mm jack commonly found on all audio devices and smartphones. Type-C can support different protocols which allows the use of adapters that can output HDMI, VGA, DisplayPort, or other types of connection.

One of the many reasons why Type-C is being favored by manufacturers is due to its small footprint. The Type-C receptacle takes up very little space on a PCB or device. It’s slightly larger than the Micro series but has much more function. New ultrathin laptops and slim smartphones are now coming standard with the Type C ports. If you were to fit a Type A socket on a smartphone, the space used by the socket alone would create too much added thickness in today’s standards.   

The Future of USB

Until wireless technology catches up to USB speeds, it is likely we will continue relying on USB.

Apple’s Thunderbolt ports are an option on the market. Thunderbolt is actually much faster than USB-C, however it requires a separate controller on the motherboard, causing a higher cost of support. The Thunderbolt is also exclusive to Apple Mac products. Their Lightning cable is similar however it connects to their iOS devices.

Generally most consumers can find the speed they need with USB-C.