Getting to Know Thunderbolt 3 and USB Type-C

With devices becoming smaller, more compact, and more powerful, the need for robust cables that can quickly power, transfer data, and perform various functions is becoming a necessity. USB has brought forth a new cable type that is one of the most powerful and versatile cables created to date, known as USB Type-C. The introduction of USB Type-C has made a substantial impact on how we use and interact with our devices, and has even influenced other technologies introduced into the market, including Thunderbolt 3. Because USB Type-C and Thunderbolt 3 are very similar appearance-wise, we wanted to take a closer look at their relationship and clear up any confusion between the two.

First, let’s get a briefing on both:

USB Type-C

USB Type-C is first and foremost a connector type that is built on the USB standard. This connector type is the latest advancement in USB that addresses improvements in functionality and versatility. One of the distinguishable features of the USB Type-C connector includes its fully reversible design, meaning any way you insert the plug, it will fit effortlessly into the receptacle.

The USB Type-C connector is fully reversible, containing 24 pins that provide the cable with its substantial power and versatile properties.

The USB Type-C connector also offers the highest power providing capabilities on a single cable. This is possible because USB Type-C cables include a Power Delivery (PD) protocol which is supported using the CC pins within the connector. This protocol allows the cable to communicate with end devices, creating a secure connection between the two where they can safely transfer and receive the requested power. Specifically, the VBUS pin provides a standard 5V, but with the PD spec, this number can reach up to 20V. With maximum current reaching up to 5A, this allows the cable to deliver up to 100W of power with an EMCA (Electronically Marked Cable Assembly) cable.

To address versatility limitations, the USB Type-C connector supports third-party protocols such as DisplayPort, HDMI, VGA, and even Thunderbolt technology using Alternate Modes, allowing cables to perform a variety of different functions all from a single connection.

For an even closer look into USB Type-C and how it’s being used today, visit our blog post, “USB Type-C is Gaining Even More Popularity” here.

Thunderbolt

Thunderbolt technology was introduced in the late 2000s by Intel, combining PCI Express (PCIe) and DisplayPort (DP) into two serial signals on a single cable. Thunderbolt was initially created to allow users to connect to external storage, high-resolutions displays, and other peripheral devices including hard-drives, docking stations, and network solutions using a high-powered cable connection.

Over the years, there have been multiple introductions of three different versions of Thunderbolt. Thunderbolt versions 1 and 2 were first implemented over the existing Mini DisplayPort connector, which upon creation was exclusive to Apple’s products.

Because the Thunderbolt technology is developed using existing connector types, Thunderbolt ports and cables feature a lightning bolt symbol signifying it supports this technology.

 Thunderbolt 3 is configured using the USB Type-C specification, but incorporates its own technology allowing it to transfer data rates up to 40 Gbps.

Thunderbolt Versions

Thunderbolt 1

Connector/Port Type: Mini DisplayPort
Data Transfer Rates: 10 Gbps
Protocols: PCI Express 2.0 and DisplayPort 1.1a

Thunderbolt 2

Connector/Port Type: Mini DisplayPort
Data Transfer Rates: 20 Gbps
Protocols: PCI Express 2.0 and Display Port 1.2

Thunderbolt 3

Connector/Port Type: USB Type-C
Data Transfer Rates: 40 Gbps
Protocols: PCI Express 3.0 and Display Port 1.2

The Thunderbolt 1 standard originally comprises of four one-way channels, two upstream channels and two downstream channels, delivering 10 Gbps per line with a maximum bandwidth of 40 Gbps. It comprises of protocols PCI Express 2.0 and DisplayPort 1.1a.  Thunderbolt 2 incorporates the same max bandwidth of 40 Gbps, but offers a substantial increase in data transfer rates of 20 Gbps per line by delivering the data using two bidirectional channels. Under Thunderbolt 1, in order to utilize a 20 Gbps allotment, users would need to combine 2 channels with 10 Gbps each, however, with Thunderbolt 2, this is no longer required. Thunderbolt 2 also incorporates protocol PCI Express 2.0 and comprises the latest DisplayPort 1.2 into its configuration.

Thunderbolt 3, the most recent development in Thunderbolt technology, has switched from using Mini DisplayPort to the USB Type-C connector. This switch has allowed the Thunderbolt technology to take advantage of a new infrastructure with enhanced speed, power, protocol support, and pixels, making it the most advanced Thunderbolt yet.

What is Thunderbolt 3 and What is its Relationship to Type-C?

The most recent Thunderbolt development, Thunderbolt 3, discontinues its previous implementation on Mini DisplayPort and transitions to an all new connector type, USB Type-C. While USB Type-C and Thunderbolt were once thought to be competing cables, they now have joined forces, making the Thunderbolt cable the fastest cable for transferring data.

Thunderbolt 3 specifically uses the physical USB Type-C connector but builds on top of its configuration using its own cabling standard. This allows it to utilize the features and high-performance capabilities of USB Type-C, while also providing its own unique capabilities. With USB Type-C becoming an industry standard, it has a broader availability within the market, making Thunderbolt 3 a more accessible feature on more personal computers – not just Apple.

Thunderbolt 3 has not only increased its bit rate to 40 Gbps, utilizing a bi-directional, full-duplex infrastructure, making it the fastest connection available.  It also comprises of the latest versions of protocols PCI Express 3.0 and DisplayPort 1.2. Thunderbolt 3 even adds support for HDMI, allowing users to transmit high-definition video and audio to connected devices, and includes support for USB 3.1 Gen 2, which is the latest USB specification that offers data transfer rates of 10 Gbps. It provides twice the display bandwidth of Thunderbolt 2, allowing devices to support four 4K displays or up to two 5K displays. Thunderbolt 3 also allows users to daisy-chain up to six Thunderbolt devices through a single port.

Because the Thunderbolt technology is supported on the Type-C connector, it is now also capable of supplying up to 100W of Power Delivery and 15W to bus-powered devices using its bi-directional power transfer capabilities. Before, the most power that was supplied over Thunderbolt was 10W, which is not an ample amount of power to charge a PC alone. Now, the Thunderbolt 3 also acts as the sole power supply for a PC.

Are Type-C and Thunderbolt 3 interchangeable?

Because these technologies both are configured using the same foundational infrastructure, there comes the question as to whether or not the Thunderbolt cable is compatible with USB Type-C ports or whether the USB Type-C cable is compatible with Thunderbolt ports. The answer is the USB Type-C cable is capable of operating within a Thunderbolt port, but this is not usually the case the other way around. This is because Thunderbolt technology was built on USB Type-C, so much of the functionality will still be used the same way. Once a Type-C connector is plugged into a Thunderbolt port, the USB 2.0 or 3.1 protocol will be activated and any Alternate Modes including DisplayPort or HDMI will be employed if applicable. In this instance, it will not be able to take advantage of the maximum speed provided by Thunderbolt. Those looking to use a Thunderbolt cable in a regular USB Type-C port will realize that it may not always be compatible. Thunderbolt has a layer of technology that includes protocols and functionalities not always offered on USB Type-C, including PCI Express that makes up the Thunderbolt technology.

Total Phase offers distinguished tools that comprehensively test and analyze a wide range of cables types, including those with USB Type-C connectors. Our Advanced Cable Tester v2 allows users to evaluate a variety of cable criteria including pin continuity, DCR/IR Drop, E-Marker verification, and signal integrity tests up to 12.8 Gbps per line. Because the Advanced Cable Tester v2 supports testing signals at 12.8 Gbps per line, it’s possible to test any cable supporting these data transfer rates using a custom module and testing profile. Whether it be for independent test labs, statistical process control, or production line settings, this cable tester will be the perfect tool to fit within your own testing and development environments.

The Advanced Cable Tester v2 tests a variety of different Type-C cable types, including Type-C to Type-C, Type-C to Standard-A, Type-C to Standard-B, and Type-C to Micro-B.

To learn more about the Advanced Cable Tester v2 can be used for your Type-C and other cable developments, please contact us at sales@totalphase.com.