USB Technology

The USB flash drive continues to be one of the most popular portable storage device around the world, with sales exceeding $2.1 Billion in 2020, and a projected CAGR of over 16% through 2027.  USB Flash drives offer capacity, speed, and size that make them ideal for many uses beyond just storage, including some perhaps unexpected uses as well.

What’s inside

A typical USB flash drive includes a USB connector, a mass storage controller, one or more flash memory chips, and a crystal oscillator, as well as additional features such as jumpers, LEDs, and switches.


Figure 1: The internal components of a typical USB Flash Drive.

  • USB Standard-A, "male" connector, which interfaces with the host computer
  • USB mass storage controller, which is a microcontroller with on-chip ROM and RAM
  • Flash memory chip, used to store data
  • Crystal oscillator, which produces the clock signal and controls data output
  • LED, which indicates active data transfer
  • Write-protect switch to enable and disable writing of data

 Both memory capacity and speed of USB drives have continued to increase, and with the advent of USB Superspeed+ devices, you can achieve transfer rates close to 900MB/sec, and storage capacities as high as 1-2TB.

USB Flash drives have now broadly incorporated the Type-C connector, which provides a smaller and thinner connector compared to the Type-A connector. The Type-C connector has a rounded, symmetric shape that fits into ports easily yet securely, and can be inserted in either orientation, as opposed to USB-A.  This connection type now opens up tremendous possibilities for data back up and storage from multiple types of mobile devices, be it smartphones, tablets and the like.



USB FLASH Drive Uses


Although the USB drive was designed as a storage solution, users are finding new purposes for its small size, capacity, and portability. For example, USB drives are making applications portable and accessible for average consumers. When you’re away from the office, you can take a USB drive containing all of your software and personal data; then, when you plug it into another computer, you have access to all of your information. When you unplug the drive, none of your personal data is left behind.

USB also makes it simple to install and update software.

High-End Applications

There are multiple grades of USB drives for different applications. For example, some manufacturers provide storage for applications where performance and reliability are key, such as in communications and networking, industrial, embedded, military and aerospace, transportation, casino gaming, and medical equipment markets.

Security Keys

Security of both personal and professional data is a constant concern. Both commercial and open-source sites offer software that turns a USB drive into a security key. A utility running on the computer constantly checks for the presence of an encrypted key stored on the USB drive. When the USB drive is plugged in, the computer operates normally. Once you remove the drive, your computer is automatically locked and requires a password for access.

Today, many manufacturers have AES 128 or 256 bit hardware based data encryption designed in to their USB flash storage offerings to provide fast and reliable data security, and to reduce the possibility of a system being compromised, and software based encryption being hacked. This all but guarantees that any sensitive data stored on the USB flash drive cannot be accessed, under any circumstances.

Manufacturers will continue to enhance USB flash drive capabilities to meet consumer demands in the future. And although cloud storage competes with USB flash storage in some use cases, USB flash drives will continue to be a solid solution with multiple uses for a very long time.

USB, USB 2.0, USB 3.0, USB 3.1, USB 3.2

Originally released in 1996, the USB (Universal Serial Bus) standard is the older of the two connection types, created by a group of companies including IBM, Microsoft, Intel, and others, and maintained by the USB Implementers Forum.

The aim of USB was to create a standard that would work across multiple different devices, unifying the myriad of technologies down to one, as the name suggests. Cables would use a specific type of connector and the wires within a cable in a specific prescribed way, and that would be largely the same across the board, with relatively few exceptions.

This reliance on a small selection of robust connectors meant it was easier for users to manage multiple devices, without having to worry about running out of ports, struggling to find the right port on their computer, or even having to find the right cable.

USB started with a data rate of 1.5Mb/s and 12Mb/s In "Low Speed" and "Full Speed" variants, though the "Full Speed" version technically arrived as part of USB 1.1. However, subsequent updates increased the transfer speeds to match the needs of consumers and enterprise users.

In 2001, USB 2.0 was released with a third tier of speed dubbed "High Speed," which boosted the bandwidth up to 480Mb/s, 40 times the speed of USB 1.1's implementation.

USB 2.0 connections were backward compatible with USB 1 variants, which allowed devices using the two different standards to continue communicating, albeit at the lower data rate. The concept of keeping the connection backward compatible with earlier iterations was kept up in subsequent releases, which makes it easier for computer users to connect hardware up without worrying about it not being compatible.

The next iteration was USB 3.0, which started with a data rate of 5Gb/s when it was introduced in 2011. As part of the standard, small changes were made to the connectors that USB 3.0 required, including the common use of blue-colored plugs and sockets to indicate compatibility with the faster speeds, though the all-important USB Type-A was still backward compatible with earlier versions.

USB 3.1 in 2014 arrived with two variants, with Gen 1 keeping USB 3.0's SuperSpeed mode and 5Gbps data rate, while Gen 2 used what was called "SuperSpeed+," and doubled the effective maximum data rate to 10Gbps. At the same time, a new connector was introduced, USB Type-C, which was an alternative option to USB Type-A for USB 3.1 and USB 3.0, but wasn't really used until the next generation.

Announced in 2017, the introduction of USB 3.2 kept support for SuperSpeed and SuperSpeed+, but also added another two transfer modes that offered connections at up to 10Gbps and 20Gbps. Furthermore, to attain the 20Gbps speed, a USB-C connection had to be used, due to standards changes that took advantage of the connector.

Just to confuse matters further, the USB Implementers Forum stepped in with a rebranding exercise in 2019.

USB 3.0 and USB 3.1 were to be given the new technical names of USB 3.2 Gen 1 and USB 3.2 Gen 2 respectively, while what was known as USB 3.2 became USB 3.2 Gen 2x2. Each was also given marketing names of SuperSpeed USB, SuperSpeed USB 10Gbps, and SuperSpeed USB 20Gbps.

At present, modern hardware that uses USB largely relies on USB 3.0 and USB 3.1, though USB 3.2 hardware started to arrive in 2019, with more appearing in 2020.

As we said before, if you take anything away from all this, all USB-C means by itself is what kind of physical connector is being used. "USB-C" on its own with no other modifiers says exactly nothing about charging, data speed, or anything else.

Connections - USB-A, USB-C, and others

While USB can use quite a few different connection types like Mini and Micro, there are only really three predominant standard versions that Apple users need to consider. They have a simple naming structure: Type-A, Type-B, and Type-C.

Since the introduction, Type-A was known as the slim rectangular connector that plugged into the Mac, PC, or USB hub, while Type-B was used on the peripheral or device end. While the Type-B connector could be switched out for a different type from the expanded connector roster, the Type-A always remained on one end.

The introduction of USB 3.0 was also an opportunity for changes to the main Type-A and Type-B connectors, adding more pins within the connector and more wires to transfer even more data. While Type-B altered its design to be taller, Type-A remained physically the same but gained extra pins in new locations, enabling it to still work with ports and connectors that didn't use them, and therefore maintaining backward compatibility.

To signify to consumers that they were meant for USB 3.0 connections, Type-A and Type-B ports and connectors were typically colored blue on non-Apple gear, differentiating them from the usual black used for the ports.

Type-C, which works with USB 3.1 and later generations, made a change to the connector's design to introduce considerably more contact points and wire pairs. While earlier connections allowed for some level of physical backward compatibility, as with Type-A, Type-C doesn't offer that.

Part of USB Type-C's design is that it eliminates the public's pain point with Type-A, in that sometimes they have to flip the cable around as they tried blindly inserting it upside down. For Type-C, the connector works in both orientations.

USB Type-C's specification also includes an improved Power Delivery specification, which can take advantage of higher wattages. Under Power Delivery, USB Type-C connections can provide up to 100 watts of power, enabling it to recharge hardware, while also using the cable for data transfers.

With the introduction of USB Type-C, device producers are shifting from using Micro USB variants in favor of Type-C, due to its compact size and relative futureproofing.

The future — USB4

In 2019, the USB IF announced it had completed its standard for USB4.

USB4 uses a Type-C connector, has a throughput of up to 40Gbps, power delivery of up to 100W, support for 4K and 5K displays, and backward compatibility with USB 3.2 and USB 2.

As a further upgrade from earlier USB generations, USB4 also supports PCIe tunneling and DisplayPort 1.4a, which can help take advantage of the higher throughput. However, if there's no support for PCIe tunneling in the host or device, the maximum bandwidth for non-display purposes is limited to 20Gbps.