USB-C Standard Analysis: Understanding the Differences Between USB 2.0, 3.0, and Thunderbolt

As Apple officially launches the iPhone 15 series in September, the USB-C port it adopts has caught public attention. USB-C, now a market standard, has made it more user-friendly and convenient for consumers when choosing cables or connecting phone peripherals. For instance, many people now opt for USB-C as the I/O port when choosing a laptop. 

 

However, despite USB-C's prevalence in the 3C product realm, controversies surrounding it have never ceased. The implementation of USB-C cable functions by manufacturers, along with official certification and differences in transmission speeds, have led to a somewhat chaotic situation. This has effectively transformed the USB-C connector into a "non-standard standard" in practice, leaving consumers confused. 

 

Therefore, with the official release of the iPhone 15 series, we present a special feature on USB-C to help readers clarify related concepts. In addition to assisting consumers in choosing the right charging and data transmission cables for the iPhone 15 series, we would like to explain the USB-C specification for all related products using USB-C ports. 

 

Table of Contents

• Why is the USB-C specification so confusing? 
• Same design but different functions 
• Unclear and difficult to identify labeling 
• Oversight 1: Is USB-C an "type of design" or a "functional standard"? 
• Definition of the USB-C interface 
• Accelerated utilization of USB-C 
• Oversight 2: Is charging via USB-C considered fast charging? 
• Charging protocol is the key 
• USB Power Delivery 
• Oversight 3: How fast is USB-C data transmission? 
• About USB version specifications 
• From 2.0 to 4, all are possible 
• Oversight 4: Can every USB-C cable transmit video? 
• USB video transmission protocol 
• Both cable and device need to support 
• Oversight 5: What exactly is the E-marker in USB-C cables? 
• Cable's ID card 
• E-marker is not a mandatory feature 
• Oversight 6: Do USB-C cable length and designdesign affect performance? 
• Cable length is important 
• Material relates to durability 
• USB support for iPhone 15 series 
• The long-awaited USB-C 
• The phased-out Lightning 
• Thunderbolt with USB-C Design 
• Creating an all-round USB-C port 
• Thunderbolt has stricter specifications 
• The further evolved Thunderbolt 5 

 

Why is the USB-C specification so confusing?

 Before explaining the various concerns about USB-C ports, it's time to reflect on why everything related to USB-C is often chaotic, and no one tries to solve these misleading or confusing issues for consumers. 

 

Same design but different functions

 

The most common problem consumers encounter with USB-C cables is that they all look the same but are often incompatible. 

From my personal experience, sometimes a USB-C cable can be used to charge a phone and connect to a computer to transfer data. However, when switched to another USB-C cable, it can only charge the phone and cannot transfer any data to the computer. Even though both cables mentioned above have USB Type-A on one end and USB-C on the other, looking identical, their functions differ greatly. 

For instance, we can project a phone's screen to an external display via a USB-C port. When switching to another phone with a USB-C port connecting to the same cable, the screen project fails, which is quite confusing. 

 

 

Unclear and difficult to identify labeling

 

Regardless of the confusion from differences in functionalities, the situation is made worse by unclear labels of the USB-C cables, even though they look similar. However, this may also be due to the widespread adoption of the USB-C standard. 

For instance, almost every HDMI cable sold has its supported version (e.g., HDMI 1.2, 1.4, 2.0, or 2.1) clearly labeled on the packaging. Similarly, Ethernet cables usually have their specifications, such as Cat.5, Cat.5e, or Cat.6, marked on the cable jacket for easy identification. 

However, if we randomly pick up any USB cable, regardless of whether it has a USB-C connector, we often find no labeling at all. This is true not only for the charging cables bundled with smartphones but also for most cables sold in the market. Consequently, consumers cannot easily determine the cable's data transfer speed, maximum charging wattage, and supported features. 

• A USB-C cable, despite of many functions, causes market confusion due to different function levels.
• Compared to the unclear labeling of USB-C, almost all HDMI cables sold in the market clearly state their supported version, leaving consumers with no confusion.
• Printing text on the cable jacket is also a common way to identify specifications. For example, Ethernet cables often have Cat.5e, Cat.6, etc., labeled, but USB cables rarely have similar designs.

 

Oversight 1: Is USB-C a "type of design" or a "functional standard"?

 

The key issue causing the confusions in USB-C specifications is that many consumers don't understand that the USB-C port itself is merely a "type of design" and does not include its supported functions.  

 Although the USB Type-A port has a rectangular symmetrical design, its design flaw requires it to transmit the data unidirectionally, causing inconvenience for consumers. This has made the bidirectional USB-C connector popular and eventually become mainstream. 

For example, in the laptop realm, having a USB-C port has almost become a standard configuration. Some thin and light laptops only provide USB-C slots, completely abandoning the previous USB Type-A. Even some small electrical appliances, such as portable fans or power banks, have switched to USB-C ports. 

The consequence of both high-end and low-end products adopting USB-C is that the consumer market becomes more chaotic. Ports and cables with different supported functions made the simple "type of design" of USB-C no longer simple, continuing to confuse consumers. 

 

Definition of the USB-C interface

 

USB-C, short for USB Type-C, is the only "reversible" port interface in the USB family compared to the most common USB Type-A, USB Type-B (usually seen on printers), and the once-popular Micro USB and Mini USB. 

The type of design of USB-C is defined by the USB Implementers Forum (USB-IF). Its interface size is 8.3 × 2.5 mm (about 0.1 in), with a total of 24 pins, evenly distributed as 12 pins in the upper and lower rows surrounding the oval-shaped port. Since the electrical definition of the pins is symmetrical, the device can correctly identify and provide related functions regardless of the insertion direction. 

In other words, when electronic product manufacturers, whether mobile phone, laptop, or even game console manufacturers, mention USB-C, they usually refer to the "appearance" of a particular port. 

 

 

Accelerated Utilization of USB-C

 

The USB-C port was initially launched alongside the USB 3.1 standard, so many people assumed that all devices and cables using USB-C connectors could support the USB 3.1 specification, with a maximum speed of 10 Gbps. However, there is no relevancy between USB-C and the USB 3.1 standard. In fact, USB-C has no support with any USB 3.1 functional standard. 

Although the statement that USB-C is only a design may seem slightly contrary to common sense, which doesn’t align with most consumers' experience, it is the most correct explanation and definition. 

USB-C is not like the HDMI port, which allows most people to intuitively understand that by plugging an HDMI cable into the HDMI port, it can be used to transmit audio and video. In other words, the four letters "HDMI" include both the design and functional definitions. On the other hand, USB-C has always been defined only by its design, without specifying its supported functions and technical standards. 

• The pin definition of the USB-C interface, with the female connector on top and the male connector on the bottom, has 24 pins symmetrically surrounding the oval shape, achieving reversibility.
• USB-C itself only represents a type of design, just like USB Type-A (left) and USB Type-B (right), and its supported functions must be additionally defined.
• Many low-end electronic products have now switched to USB-C ports, such as portable fans or power banks, but their functions are mostly incomplete, further aggravating consumer confusion.

  

USB Type-C® Cable and Connector Specification – From USB – IF  

 

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Oversight 2: Is charging via USB-C considered fast charging?

 

Many consumers associate "phone supporting fast charging" with "having a USB-C charging port." However, these two things are not relevant. Why do we often have this misunderstanding? 

 

 

Charging protocol is the key

 

 

Following the premise that "USB-C is only a type of design," whether a phone supports fast charging is not determined by whether the device using USB-C as the charging port. Instead, it depends on which charging protocol standardizes the charger, phone, and cable, and how much charging current they can provide to meet the conditions for enabling fast charging. 

Without using any charging protocol, the current a phone obtains through the USB port will be the standard 5V, 0.5A (USB 2.0), or 5V, 0.9A (USB 3.0). Regardless of the charger, USB port, cable, or phone, they can at least provide or maintain a basic charging capacity of 2.5W or 4.5W. 

When the charger's specification is upgraded, the USB cable can start supplying higher-wattage current to the device, such as the common 10W, 15W, and 18W. This has encouraged major phone manufacturers to introduce self-developed fast charging protocols, pushing the charging wattage upward. 

 

USB Power Delivery

 

As manufacturers have their own charging standards, the USB-IF has chosen to revise the USB Power Delivery (USB-PD) specification to address the fast-charging demand of phones and avoid monopoly and consumer confusion. 

Starting from USB-PD 2.0, the charging connector's design is defined as USB-C. In other words, only cables with USB-C ports on both ends can support USB-PD 2.0 and above. However, the USB-PD 1.0, which does not limit the connectors, has the same 100W charging wattage limit as the 2.0. 

Although the subsequent USB-PD 3.0 still has a 100W power supply limit, it adds the Programmable Power Supply (PPS) feature, which is compatible with manufacturers' fast charging standards within a certain range. The latest USB-PD 3.1 classifies the power supply intensity within 100W as the Standard Power Range (SPR) and increases the extended power range to 240W. 

In conclusion, devices using USB-C connectors under the USB-PD specification can support charging speeds of up to 48V and 240W, despite manufacturers' proprietary protocols. This depends on whether the charger, terminal device, and cable support it. However, the USB-IF stipulates that when the charging power exceeds 60W, the matched USB-C cable must have a capacity of at least 5 amperes to avoid safety issues caused by excessive current. 

 

• The key to phone charging speed is not determined by the USB-C connector, but in the charging, protocol adopted between the phone and the charger. For example, Realme and OPPO have proprietary 240W fast charging technologies.
• Most chargers usually specify the supported power combination protocol. When the charging cable is connected to the terminal device, it will start communicating the charging protocol and eventually charge with one of the combinations.
• The USB-IF stipulates that USB-C cables supporting 60W or higher power supply must have a current capacity of at least 5A, mainly for safety considerations. 

 

Oversight 3: How fast is USB-C data transmission?

  

Since USB began its design and development, it has been more than 28 years. The USB 1.0 standard, officially launched in 1996, had a speed of only 1.5 Mbps. The most popular USB 2.0 version is 480 Mbps, and the popular USB 3.2 Gen 2×2 can reach 20 Gbps. 

 

So, how fast is USB-C? With the main concept of "USB-C is only a type of design," the maximum transmission speed a USB-C port depends on the standard supported by the device itself. Just as the charging wattage of USB-C relies on the USB Power Delivery capabilities, the transmission speed of USB-C naturally depends on which USB version the device is using. 

 

 

 

About USB version specifications

  

Although USB is one of the most used transmission interfaces in our daily life, most people don't have a deep understanding of it. However, at least in terms of versions, we could simply distinguish between USB 1.0, 2.0, and 3.0 in the past until the USB-IF actively made everything confusing.  

The mainstream USB 2.0, officially named Hi-Speed USB, has a transmission speed of 480 Mbps and is the most standard USB speed specification. Its USB Type-A connector is mostly white. The USB 3.2 Gen 1 standard, "formerly" known as USB 3.0, has a transmission speed of 5 Gbps. The USB 3.2 Gen 2, "formerly" known as USB 3.1, has a transmission speed of 10 Gbps. The USB 3.2 Gen 2×2 standard doubles the speed to 20 Gbps, and the USB Type-A connectors mentioned above are generally blue.  

Regardless of why the naming of USB 3.0 and 3.1 are inexplicably deprecated and all of them "upgraded" to USB 3.2. While a blue USB Type-A port has three different maximum speeds, which is indeed confusing. However, when these USB speed protocols are applied to USB-C connectors without any color labeling, the reality is that all four speed specifications mentioned above, can be presented in the form of USB-C ports, even with the foreseeable USB4 standard. 

 

>>> USB-IF : https://www.usb.org 

>>> USB 2.0 Standard Specification By USB-IF  

 

From 2.0 to 4, all are possible

 

Since the USB-C type of design is compatible with the USB 2.0 specification, the maximum data transmission speed supported by USB-C ports or cables may be the 480 Mbps with USB 2.0 standard. Of course, it may also be the 5 Gbps, 10 Gbps, or 20 Gbps of the USB 3.2 family, and even the 40 Gbps with upcoming USB 4. It depends on which specification the USB-C port on the device supports and to which speed standard the cable corresponds. 

Moreover, although USB standards are backward compatible, for example, when a cable with USB 3.2 Gen 2×2 specification is plugged into a USB 2.0 port on a computer and the other connector plugging into a phone supporting USB 3.2 Gen 2, there will be no issues. However, the data transmission speed will be limited to the lowest side, which in this case is the 480 Mbps of the USB 2.0 port on the computer. Therefore, consumers can only achieve the theoretical maximum transmission speed by correctly matching the port specifications on the device with the cable. 

 

• In the past, we could simply distinguish between USB 2.0 and 3.0 through the color of the USB port, but with the update of standards and the emergence of USB-C, this method is no longer very useful.
• To solve the difficulty for consumers to identify USB transmission speed and charging wattage, the USB-IF specially designed a series of new icons for manufacturers to apply to related products in the future.

 

Oversight 4: Can every USB-C cable transmit video?

 

Along with fast charging and data transmission, one of the most critical prerequisites is what conditions need to be satisfied to transmit audio and video content through the USB-C port. However, the answer to this question is indeed more complicated than imagined. 

 

USB video transmission protocol

 

In terms of charging, USB has the Power Delivery specification, and in terms of transmission speed, USB has different version standards, such as USB 2.0, 3.2, etc. What about video and audio transmission? Of course, there is also a standard called DisplayPort Alternate Mode, abbreviated as DP Alt Mode. Some people also call it the DisplayPort alternate mode. 

 

To explain DP Alt Mode, we must start with DisplayPort. As a well-known audio and video transmission standard alongside HDMI, DisplayPort has been applied in many devices, such as laptops, mobile phones, and monitors. Although it is relatively rare in TV products, DisplayPort's support for ultra-high bandwidth has made it the preferred specification for computer gamers. For example, the latest DisplayPort 2.0 protocol can support transmission speeds of 80 Gbit/s. 

 

DisplayPort, which evolved from VGA and DVI video interfaces, also has its own dedicated transmission interface. The most common design is a truncated rectangle, and there is also a smaller, nearly square Mini DisplayPort. 

 

However, in 2014, the Video Electronics Standards Association (VESA), responsible for developing the DisplayPort standard, announced that it would allow the USB-C interface to support the transmission of DisplayPort standard audio and video signals through the Alternate Mode, hoping to further expand the usage scenarios. This is DP Alt Mode. 

 

 

Both cable and device need to support

 

 

 

USB-C's DP Alt Mode currently supports DisplayPort 1.2, 1.4, and 2.0 standards. Considering the bandwidth required for signal transmission, USB-C cables need to support at least the USB 3.2 Gen 2 standard, that is, a transmission bandwidth of 10 Gbps or above, to support DP Alt Mode for transmitting audio and video content. 

In addition, devices that output DisplayPort signals, such as the USB-C interface of laptops or mobile phones, must also support the DP Alt Mode standard to smoothly transmit the screen to a monitor with DisplayPort signal input using a cable. 

 

Benefiting from the improvement in USB standards in terms of speed, the future USB4 will further integrate and upgrade to DP Alt Mode 2.0, supporting all the functions of the DisplayPort 2.0 standard and outputting up to 16K resolution video signals, which is quite amazing. 

 

In addition to DP Alt Mode, the USB-C interface also has other alternate modes that can be used to transmit audio and video signals, such as MHL Alt Mode and HDMI Alt Mode. However, these two standards are even rarer than DP Alt Mode, so we will not dive in today.  

• Native DisplayPort has two interfaces, namely standard DisplayPort (right) and Mini DisplayPort (left). While USB-C was included later.

• According to VESA's explanation, with the dual heads of the USB-C cable, DP Alt Mode can transmit DisplayPort audio and video signals, support USB-PD and data transmission simultaneously.
• Monitors with USB-C DP Alt Mode functionality is not rear now, especially in high-end monitor products, allowing consumers to achieve the audio-visual transmitting with a single USB-C cable.

 

Oversight 5: What exactly is the E-marker in USB-C cables?

  

Many consumers looking for USB-C cables may have come across the term "E-marker." Some manufacturers even use an ‘E-marker’ as a selling point, marking it on the product to attract buyers to purchase with a higher price. 

But what exactly is an E-marker? Does the presence of an E-marker make a big difference in the power supply, data transmission, and supported functions of USB-C cables? Read on, and you'll understand.  

 

Cable's ID card

 

The so-called E-marker, short for "Electronically Marked Cable," is a special chip embedded in the USB-C cable. When the connected device reads the E-marker chip in the cable, it can understand the various attributes of the cable itself, such as power transmission capability, data transmission capability, video transmission capability, and proprietary ID information. 

Consumers can simply understand the function of the E-marker chip in USB-C cables as the "ID card" of the USB-C cable. It records everything about that USB-C cable. When a USB-C cable with an E-marker chip is connected to terminal devices such as computers or mobile phones, the E-marker will actively provide various electronic identification tags, allowing the connected device to respond with the corresponding charging power, transmission speed, and audio-visual transmission protocol. It can even dynamically adjust to maximize the cable's performance. 

 

 

 

E-marker is not a mandatory feature

 

Although installing a chip in the cable sounds advanced, for manufacturers, an additional E-marker chip will increase the production cost dramatically. Therefore, the USB-IF does not mandate that every USB-C cable must carry an E-marker chip. The E-marker chip becomes a standard feature of the cable only under specific conditions. 

According to the USB-IF specification, USB-C cables with a current capacity greater than 3 amperes must carry an E-marker chip for safety considerations. In other words, the 5A and 6A USB-C cables on the market all carry an E-marker chip inside to identify and configure the charging protocol with terminal devices, preventing damage to the device due to the excessive current. This is why cables with an E-marker chip are often simply defined as "fast charging cables."  

In addition, the requirement for E-marker chips is not limited to USB-C to USB-C cables. Whether it is USB Type-A to USB-C or even USB Type-B to USB-C, when the cable is expected to provide a current exceeding 3 amperes, it must be equipped with an E-marker chip. 

If the cable itself with a current capacity of less than 3 amperes but supports video output, then an E-marker chip is required, according to the USB-IF regulations.  Otherwise, the devices will not recognize the protocol to transmit audio and video signals. 

Can a USB-C cable with an E-marker chip achieve the 5 Gbps data transmission speed of the USB 3.2 Gen 1 standard? The answer is not certain. Practically, USB-C cables with USB 2.0 standard can also be equipped with an E-marker chip. Few manufacturers will do because it will increase additional production costs. 

 

• If a small IC chip is found after opening a USB-C cable, it is usually the E-marker, which will contain various information about that USB-C cable.
• To know the E-marker information of a USB-C cable, some professional tools can be used to read it, but this is of little significance to general consumers. (Image source: Chargerlab)
• As long as the current capacity supported by the cable exceeds 3A, it must have a built-in E-marker chip. Therefore, USB-C cables with an E-marker are often simply defined as fast charging cables.

 

Oversight 6: Do USB-C cable length and design affect performance?

 

There are so many USB-C cables on the market, whether long or short; round or flat; solid color or colorful; braided or plastic, consumers can usually choose freely according to their needs. However, as USB transmission speeds accelerate and charging wattages increase significantly, the cable's performance may be affected by the design, leading to a compromised user experience, despite looking good on the outside. 

 

 

Cable length is important

 

A cable with extra-long length will affect its performance. Electrical signals will naturally degrade when passing through the long copper wire, resulting in a decrease in data transmission speed.  USB-C cables, like network cables and HDMI cables, have limitations on length. 

Although the USB-IF does not have a mandatory requirement for the length of USB-C cables, USB-C to USB-C cables using the USB 2.0 protocol should not exceed 4 meters in maximum length as recommended. USB 3.2 Gen 1, which reaches 5 Gbps, should not exceed 2 meters; and USB 3.2 Gen 2, which reaches 10 Gbps, is recommended not to exceed 1 meter in cable length. 

The faster the data transmission speed, the greater the cable length limitation will be. That is why it is difficult to make longer cables. Therefore, when consumers choose cable products that support the USB 3.2 standard, they must be aware of the length to make sure the transmission speed is as expected. Otherwise, the cable may not function properly after connecting to the terminal device. 

 

 

Material relates to durability

  

Since cable length affects data transmission speed, what about power supply? The answer is that there may be some impact, but it will not be as significant as "speed drop," at least not as noticeable in terms of user experience. 

As the relevancy between length and power supply capability is slim, longer USB-C cables on the market usually boast the charging function with a simple name of "charging cable," which rarely guarantees data transmission speed or stability. However, it is still recommended that consumers do not use excessively long cables when using high wattage charging function and choose cables with higher current capacity, such as 5A or 6A, which will be safer. 

Regarding the material of the cable, whether it is nylon braided cable, steel cable, PVC cable, or TPE cable, if the copper wire used inside is not in low quality and the workmanship is proper, there will be no impact on transmission and charging performance. However, I personally do not recommend choosing "flat cables" because their anti-interference ability is relatively weaker than round cables, and the internal copper wire usually must withstand greater pressure, resulting in a generally shorter lifespan. 

• The types and styles of USB-C cables on the market are so dazzling that it is not easy to choose a transmission cable or charging cable that meets one's needs.
• Due to the electrical characteristics of cables, whether it is network cables or USB-C and other types of cables, I always do not recommend purchasing flat cables. Common round cables are still a more reliable choice.
• According to Infineon's recommendations, USB 3.2 Gen 2 cables with a maximum speed of 10 Gbps should not exceed 1 meter in length, but this is not a mandatory requirement of USB-IF.

 

USB support for iPhone 15 series

 

With the official launch of the iPhone 15 series, Apple has officially switched to the USB-C port for its phone products, formally ending the history of its proprietary Lightning connector, which has been in development for more than 10 years. 

What is the difference between the iPhone 15 with a USB-C slot and the previous Lightning connector? Are there any differences in the USB-C ports of the four phones: iPhone 15, iPhone 15 Plus, iPhone 15 Pro, and iPhone 15 Pro Max? Is the change from Lightning to USB-C good or bad for consumers? Next, we will briefly explore these questions. 

 

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The long-awaited USB-C

 

The iPhone 15 series' support for USB-C is not uniform. The entry-level iPhone 15 and iPhone 15 Plus only support the USB 2.0 speed standard, which means the maximum data transmission is only 480 Mbps. As for the iPhone 15 Pro and iPhone 15 Pro Max, due to the addition of a USB 3 controller in the A17 Pro chip, the maximum data transmission speed can reach 10 Gbps. 

For users who pursue high-speed data transmission, such as exporting ProRAW and ProRes images taken by the phone to the computer, it will be a better choice to go for the iPhone 15 Pro and iPhone 15 Pro Max. However, it is also important to remember to purchase the corresponding cable to take advantage of the 10 Gbps transmission speed. 

However, the main benefit of the iPhone switching to USB-C is not the improvement in data transmission speed but that consumers can finally buy one less adapter, carry one less charging cable, and have more peripheral accessory options. 

The entire iPhone 15 series supports DP Alt Mode, so consumers can easily output the phone screen to an external display via USB-C. At the same time, the USB-C interface also makes it more convenient for users to connect devices such as flash drives, external hard drives, and SD card readers to the phone. These additional benefits are far more noticeable than the improvement in transmission speed. 

 

 

The phased-out Lightning

 

Lightning and USB-C are both reversible connectors. Although they look similar, they are not compatible, and there are significant differences in size and pin design. The transmission speed of the Lightning connector on most Apple devices only complies with the USB 2.0 standard, which is a maximum of 480 Mbps. However, there are still some exceptions. For example, the first and second generations of the 12.9-inch iPad Pro can obtain a transmission speed of 5 Gbps through the Lightning connector, compatible with the USB 3.2 Gen 1 specification. The highest known charging speed is currently 27W.  

From the above description, it is not difficult to find that Apple can actively revise the Lightning connector in terms of data transmission speed or charging wattage to release more performance. Therefore, compared with USB-C, it is not completely at a disadvantage. It's just that USB-C has evolved faster in the past period, with higher transmission bandwidth and charging speed, and the specifications are more open and transparent. 

Although the main reason Apple will switch the iPhone's Lightning connector to USB-C is due to the European Union's environmental protection requirements, Apple has always been one of the main members of the USB-IF and has even made significant contributions to the development of USB-C specifications. Therefore, many people believe Apple's opposition to USB-C is unreasonable. The company is even a major promoter of USB-C. For example, MacBook made USB-C the only port very early on. It's just that there are deeper considerations in the mobile phone market, such as the interests of the ecosystem and peripheral manufacturers. 

 

• Apple's iPhone 15 switching to the USB-C port can indeed be regarded as a key moment in the development history of smartphones. Of course, this also means that the physical transmission interface of the Apple ecosystem is finally unified.
• The USB-C port specifications of the iPhone 15 and iPhone 15 Pro are different. The latter benefits from the USB 3 controller in the A17 Pro chip, and the data transmission speed can reach 10 Gbps. 

 

Thunderbolt with USB-C design

 

We have repeatedly mentioned that "USB-C is only a type of design." At the same time, USB-C can also support video output standards such as DisplayPort, MHL, and HDMI through alternate modes. However, in addition to this, there is another standard that also uses USB-C as the interface, which is Thunderbolt, promoted by Intel. 

 

Creating an all-round USB-C port

 

In 2015, Intel announced that starting from Thunderbolt 3, the form of the port would be changed to USB-C, breaking away from the previous Mini DisplayPort. Not only did the functionality become more comprehensive and compatible with USB specifications, but it also accelerated the utilization of the Thunderbolt standard, which has no limit to high-end devices. In 2020, Intel launched Thunderbolt 4, even showing greater ambition to try to create an "all-function USB solution." By using a simple identification method, consumers can get rid of the confusion of existing USB-C specifications and enjoy the most complete USB port-related functions. 

 

 

Thunderbolt has stricter specifications

 

Intel points out that USB-C and Thunderbolt cannot be mixed up. USB-C cables or terminal devices must meet the minimum requirements for data transmission, power supply, and video transmission to obtain Thunderbolt certification. Consumers only need to recognize the Thunderbolt lightning symbol on computers, laptops, or cables to enjoy the complete functions that the USB standard should have, including high-speed data transmission, high wattage charging, and top-notch audio-visual output. 

 

For example, although Thunderbolt 4 is designed in accordance with the USB 4 standard, the difference between the two is that the standard specifications of Thunderbolt 4 are more restricted. Every port and cable with Thunderbolt 4 certification must support a 40 Gbps data transmission speed, provide at least 15W power supply to connected devices, and support up to 140W. It also supports the screen output of two 4K, 60Hz monitors. However, these specifications are mostly "optional" in the USB4 standard but "mandatory" in the Thunderbolt 4 certification. 

 

 

The further evolved Thunderbolt 5

 

A while ago, Intel publicly announced the Thunderbolt 5 interface, which has a stricter certified specification than the next-generation USB4 v2 standard. It not only requires that the communication protocol of certified products be upgraded to PCIe Gen 4 but also that the bidirectional data transmission bandwidth must be 80 Gbps, and the unidirectional transmission bandwidth must reach 120 Gbps. The power supply limit is also raised to 240W, and it supports the screen output of three 4K, 144Hz monitors. At the same time, Thunderbolt 5 is also compatible with USB4 v2 and DisplayPort 2.1 standards. 

Intel stated that the goal of Thunderbolt 5 is to allow consumers to use high-speed external devices, high-resolution screen output, and high-power charging functions through a single cable. Future products equipped with Thunderbolt 5 will mainly be laptops, but the actual time to land on the market is currently unknown. In the face of the chaotic USB-C specifications on the market, Thunderbolt's vision is still to create a complete solution. 

• Thunderbolt with USB-C design, due to more stringent certification standards than USB-C, consumers only need to recognize the lightning symbol to get complete USB-C function support.
• Intel recently released the latest Thunderbolt 5 standard. In addition to the bidirectional transmission bandwidth reaching 80 Gbps, the unidirectional bandwidth has an amazing 120 Gbps.
• Thunderbolt's high compatibility can be used for data transmission, device charging, network connection, and video output. One standard or even a single cable can accomplish multiple tasks.

 

The Key Differences Between USB 2.0, 3.0, and Thunderbolt

 

A table to compare the differences among USB 2.0, USB 3.0, and Thunderbolt 1, 2, 3, 4, and 5 based on their key specifications and features. This comparison will include aspects such as data transfer speed, connectivity options, power delivery capabilities, and any additional notable features. 

Specification	USB 2.0	USB 3.0	Thunderbolt 1	Thunderbolt 2	Thunderbolt 3	Thunderbolt 4	Thunderbolt 5 (assumed)
Release Year	2000	2008	2011	2013	2015	2020	TBD
Data Transfer Speed	480 Mbps	5 Gbps	10 Gbps	20 Gbps	40 Gbps	40 Gbps	Expected >40 Gbps
Power Delivery	Up to 2.5W	Up to 4.5W	Up to 10W	Up to 10W	Up to 100W	Up to 100W	TBD
Connector Type	USB-A, USB-B, Mini-USB, Micro-USB	USB-A, USB-B, Micro-USB, USB-C	Mini DisplayPort	Mini DisplayPort	USB-C	USB-C	USB-C
Video Support	No	Yes, HDMI, DVI via adapters	Yes, DisplayPort	Yes, DisplayPort	Yes, DisplayPort, HDMI via adapter	Yes, DisplayPort, HDMI via adapter	TBD
Daisy Chaining	No	No	Yes, up to 6 devices	Yes, up to 6 devices	Yes, up to 6 devices	Yes, up to 6 devices	TBD
Backward Compatibility	USB 1.1	USB 2.0	Thunderbolt 1	Thunderbolt 1	USB 3.2, Thunderbolt 1, 2	USB4, Thunderbolt 3	TBD
Notable Features	Wide adoption	Improved power delivery, blue connectors	Bi-directional data transfer, video support	Bi-directional data transfer, video support	Supports dual 4K or single 8K, PCIe data transfer	Increased minimum requirements for video and data, mandatory USB4 support	Advanced features expected, possibly faster data transfer and improved power delivery

Thunderbolt versions aim to increase data transfer speed, power delivery, and versatility with each iteration, especially with the adoption of the USB-C connector from Thunderbolt 3 onwards, unifying the interface for a variety of devices. Thunderbolt 4, while not increasing the maximum data transfer speed beyond what Thunderbolt 3 offers, improves minimum performance requirements, security features, and multi-port accessory architecture.