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What is a USB Cable?

We know that technology evolves faster and further every day and it can sometimes feel overwhelming. That’s why we’ve partnered with StarTech.com, a global leader in manufacturing top-quality USB cables and connectivity solutions, to bring you this USB Cable Guide.

Here, you’ll learn everything you need to know about the various types of USB cables, what the USB versions mean for transferring your data, and how they work.

USB stands for Universal Serial Bus and is an umbrella term used to describe the most common port type: the rectangular USB, known as USB A. Typically, USB ports are found across multiple devices, such as phones, PCs, and gaming consoles.

Initially developed in the mid-90s, the USB connection was created to standardize ports for peripherals. This is so secondary devices, like printers and keyboards, can connect to a wider range of computers and hosts, rather than a select few with specific receptacles.

Today, there are a variety of USB types, but the main use of all USBs has remained the same: to transfer data and power. Over time, new versions have been released to improve transfer speeds and power output.

StarTech.com are the experts when it comes to how this technology works. The industry leaders explain a USB 2.0 cable connection like this:

“If you were to open up a USB cable, you would notice 4 different USB wire colours: white and green, which carry data, and red and black, which are used for power. Red carries 5 volts and acts as the positive wire, while black is the negative wire, otherwise known as the ground wire.

Each type of USB connection (USB cable type A, B, C, micro and mini) has a pinout system, these are the small metal strips inside the connector, designed to access each of these wires and their capabilities.”

Over the last 25 years, there have been several different USB cables and iterations, depending on the USB protocol. The USB started with version 1.0, which transfers up to 12Mbps and was released in 1995. The latest today is USB version 4, which transfers up to a massive 40Gbps.

StarTech.com know that users want the best USB for the job, which is why they have created a table below to help decipher the speed and capabilities of each version.

As with USB versions, the shape of the USB connection has also seen drastic changes over the years. With each new evolution of USB type, their form factor generally becomes smaller to accommodate for new, much thinner devices that are popular during the time of release.

The USB C design, which is the latest USB release, is unique because it’s the only USB that fits into another port type not specifically created for it: Thunderbolt 3. They are both the same shape and users can employ Thunderbolt 3 and USB C cables and ports interchangeably. All other male and female USB connector types only fit their corresponding male and female ports. For example, a USB port type b will only accept a USB type B connector.

The version or speed of the technology is dictated by the host device, connecting peripheral, and the version of the USB 3.0 cable, not the shape of the port.

Backwards compatibility means that the latest version of something is still capable of using previous versions. For example, a USB A 3.0 port is capable of recognising and utilising a USB A 2.0 peripheral.

For the newer USB C, it’s still possible to connect older USB supported devices to a USB C port or host, via an adapter. StarTech.com provide an extensive range of 90 Degree USB Cable, which can be used if the host and peripheral have different port types. Adapters, or connectors, can be found for all USB types and are not limited to USB C.

When using previous USB versions, the performance is limited to the earliest version that’s being used. For example, if you want to transfer files from a 2.0 USB A enabled hard drive to a laptop with USB A 3.0 ports, the transfer rate (USB speeds) would be limited to 480Mbps.

USB-C is the latest advancement in USB connectivity and has been dubbed by many as “future proof.” It is conveniently reversible and has a much more compact shape compared to previous USB cable types. A USB C cable not only deals with data and power, but also video. It supports multiple protocols and carries DisplayPort and HDMI signals (when in Alt mode), as well as Thunderbolt 3 for equipped devices. Also, like other USBs, it’s capable of backwards compatibility from USB 1.1, but functions with the latest USB 3.2 Gen 2.2 devices as well.

This type of connector looks and is physically the same as a Thunderbolt 3 port. Thunderbolt 3 and USB C ports and cables can be used interchangeably and utilised for data transfer, power output, and video. When using a Thunderbolt 3 port with a USB C cable, users can charge full-size electronics with up to 100W of power output. Even better, the top data transfer speed is 40Gbps with a Thunderbolt 3 port, meaning you can be more productive.

Universal Serial Bus (USB) was developed in the 1990s in an effort to simplify the connections between computers and peripheral devices. It has become widely popular due to its compatibility with many platforms and operating systems, its low cost of implementation, and its ease of use. Most computers that are built today come with several USB ports, and USB is the interface of choice for most home and office peripherals including printers, cameras, modems, and portable storage devices.

USB standards are developed and maintained by an industry body called the USB Implementers Forum (USB-IF). In its original specification, USB defined only two connector types: A and B. Revisions to the specification and demands on manufacturers have expanded the breadth of connectors used for USB devices, but the majority of USB products still use these A and B connector interfaces.

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. It was not intended for use as an “upstream” connector on a peripheral device. This is critical because a host controller or hub is designed to provide 5V DC power on one of the USB pins. Though not that common, A-A cables are used to connect USB devices with an A-style Female port to a PC or another USB device, and for data transfer between two computer systems. Note: Typically an A-A cable is not intended to connect two computers together or to connect a USB hub between two computers. Doing so may cause irreparable damage to your computers and may even present a fire hazard. Check with the manufacturer before using an A-A cable for data transfer.

The B-style connector is designed for use on USB peripheral devices. The B-style interface is squarish in shape, and has slightly beveled corners on the top ends of the connector. Like the A connector, it uses the friction of the connector body to stay in place. The B-socket is an “upstream” connector that is only used on peripheral devices. Because of this, the majority of USB applications require USB OTG Cable.

The USB-C or USB Type-C connector is the newest USB connector on the market. The USB-C connector has a reversible/symmetrical design and can be plugged into any USB-C device using either end. A USB-C cable is capable of carrying USB 3.1, USB 3.0, USB 2.0, and USB 1.1 signals. The USB-C is commonly paired with the USB-A, USB-B, USB Micro-B, and other USB connectors when supporting previous versions of the USB specification. USB-C can be adapted to work with each of these legacy connectors. When connecting two USB 3.1 devices, the USB-C cable will support data transfer rates that are twice the speed of existing USB technology (up to 10Gbit/s), enhanced power delivery of up to 20 volts, 5 amps, and 100 watts for power and charging, and built-in support for DisplayPort video and four channel audio (speaker and microphone).

One drawback to the B-style connector is its size, which measures almost a half inch on each side. This made the B-style interface unsuitable for many compact personal electronic devices such as PDAs, digital cameras, and cellphones. As a result, many device manufacturers began the miniaturization of USB connectors with this Mini-b. This 5-pin Mini-b is the most popular style of Mini-b connector, and the only one recognized by the USB-IF. By default, a Mini-b cable is presumed to have 5 pins. This connector is quite small, about two-thirds the width of an A-style connector. It is also specified for use in the newer standard called USB On-The-Go which allows peripheral devices to communicate with the presence of a host controller.

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.

Just about any computer that you buy today comes with one or more Universal Serial Bus connectors. These USB connectors let you attach mice, printers and other accessories to your computer quickly and easily. The operating system supports USB as well, so the installation of the device drivers is quick and easy, too. Compared to other ways of connecting devices to your computer (including parallel ports, serial ports and special cards that you install inside the computer’s case), USB devices are incredibly simple.

­In this article, we’ll look at USB ports from both a user and a technical standpoint. You’ll learn why the USB system is so flexible and how it’s able to support so many devices so easily — it’s truly an amazing system.

Most computers that you buy today come with at least one or two USB sockets. But with so many USB devices on the market, you easily run out of sockets very quickly. For example, you could have a keyboard, mouse, printer, microphone and webcam all running on USB technology, so the obvious question is, “How do you hook up all the devices?”

The easy solution to the problem is to buy an inexpensive USB hub. The USB standard supports up to 127 devices, and USB hubs are a part of the standard.

A hub typically has four new ports, but may have many more. You plug the hub into your computer, and then plug your devices (or other hubs) into the hub. By chaining hubs together, you can build up dozens of available USB ports on a single computer.

Hubs can be powered or unpowered. As you’ll see on the next page, the USB standard allows for devices to draw their power from their USB connection. A high-power device like a printer or scanner will have its own power supply, but low-power devices like mice and digital cameras get their power from the bus in order to simplify them. The power (up to 500 milliamps at 5 volts for USB 2.0 and 900 milliamps for USB 3.0) comes from the computer. If you have lots of self-powered devices (like printers and scanners), then your hub doesn’t need to be powered — none of the devices connecting to the hub needs additional power, so the computer can handle it. If you have lots of unpowered devices like mice and cameras, you probably need a powered hub. The hub has its own transformer and it supplies power to the bus so that the devices don’t overload the computer’s supply.
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