The Ultimate Guide to USB Cables by StarTech.com

What is a USB Cable?

USB, or Universal Serial Bus, is one of the most common ports and protocols featured on devices. Initially developed in the mid-90s, USB was created to standardize the ports peripherals like printers and keyboards used to connect to a computer. Today, variations of the port are used on devices like cellphones, printers, cameras, and video game controllers to interact with a host device.

How do USB cables work?

USB cables transfer power and data to devices that require it and provide an immediate connection between peripherals and host computers. If you were to open a USB cable, you would notice 4 different coloured wires: white and green, which carry data, and red and black, which are used for power (red being the positive wire that carries 5 volts, and black being the negative or ground wire).

Each USB connector (types A, B, C, micro and mini) has a pinout designed to access each of these wires and their capabilities.

USB Version types

There are several versions of USB and, depending on the USB protocol, data transfer speeds will vary. For example, a USB 2.0 port can reach speeds up to 480mbps, while a USB 3.1 Gen 2 port can transfer at speeds of 10Gbps. Below is a chart to help decipher the speed and capabilities of each USB version.

USB Types Explained

The USB connector has changed drastically over time, with each new USB “type” having a different connector and port shape than previous versions. USB types A, B, micro and mini all had specific connector shapes that fit into their ports in a specific direction. Some types, like USB-B, are larger and bulkier than others. The latest release, USB Type-C is a compact connector that is conveniently reversible and easily accommodates the thinner devices that are popular today.

The port shape, or USB type, does not necessarily indicate the version of USB that’s carried through it. For example, USB-A is the standard rectangular port that many people know and recognize, and while this connector can support up to USB 3.2 data rates, however, depending on the device it is paired with, it might support data rates only up to USB 2.0 speeds. The version or speed of the technology is dictated by the host device and connecting peripheral, not the shape of the port.

What does backwards compatible mean?

USB 3.0 ports are backwards compatible with all earlier versions of USB, so with the help of adapters, it is easy to remain connected to older peripherals after you’ve upgraded devices. With USB-C, for example, while the port is physically different, with a simple adapter you can easily connect your USB-A tech tools to your USB-C devices. With that said, it will downgrade performance to that supported by the device. For example, if you are trying to transfer files from a USB-A flash drive to your new USB-C laptop, with the help of a USB-C to USB-A hub, your device will be able to connect to the drive and read the data. When transferring the files, however, if the flash drive is USB 2.0, the maximum speed your files will transfer at will be 480 Mbps, not the 10 Gbps standard expected from USB-C.

USB Connector Types

Below is a short explaination about the most popular USB types available on the market:

FAQs

Can I use a USB cable to charge my phone?

Yes, most mobile devices depend on USB to charge, however the USB types change depending on the device. Most android phones will use Micro-USB or USB Type-C on the phone end and charge via USB-A in either a charge hub or computer. iPhones use a lightning connector on the device and charge via lightning to USB-A.

What does 'OTG' mean?

USB On-the-Go, or “OTG” is a specification that allows two USB devices to be connected and switch between host and device. For example, with a USB OTG cable, users can connect a USB mouse to their smartphone or tablet and use it with their mobile device. The OTG specification allows what would normally be considered a “device” to act as a “host” for other devices to connect to and interact with.

Which USB cable is best for charging?

There are particular ports on docking stations, charge hubs and computers commonly referred to as “fast charge ports.” These ports often boast more power in order to charge mobile devices like smartphones and tablets, quickly and efficiently. Make sure to check the product details for full charge speed specifications.

Are USB ports colour coded?

The colour of the USB connector is a common way to recognize which version of USB a cable or port is. White indicates USB 1.0, black USB 2.0 and blue USB 3.0. It is important to note, however, that this identification structure is not foolproof as it is up to the manufacturer of the particular USB device whether to include the colour indicators or not.