New USB-C Type 2.1 Cable and Connector Specification

All about the new USB-C type 2.1 specification with high power transfer and faster data speeds.

USB C cable TechReviewer

Last Updated: July 14, 2021

Written by Brandon Jones

What Is USB-C Type 2.1?

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USB-C Type 2.1 is a USB-C cable and connector specification which allows for high power transfer and faster data speeds.

The connector shape is the same as other USB-C connectors. Newly added labels indicate whether a specific cable supports Standard Power Range (SPR) or both SPR and Extended Power Range (EPR).

USB4 and Thunderbolt 4 will be the first to support the faster speeds and higher power of the USB-C Type 2.1 cables and connectors.

What Is New in the USB-C Type 2.1 Specification?

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Additions in Type 2.1 Unchanged in Type 2.1
Higher power delivery USB-C cable connector shape
Faster video/data speeds
Arcing mitigation

What Is the Voltage and Wattage Rating of a USB-C Type 2.1 Cable?

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USB-C type 2.1 is rated to deliver up to 240 watts of power.

The previous version was rated to deliver up to 100 watts of power, so type 2.1 is a significant upgrade.

The increased power will allow you to charge capable laptops and phones more quickly using a USB C cable.

Not all USB-C Type 2.1 cables will be rated for this Extended Power Range (EPR) specification of 240 watts, though, since it's optional for this new specification.

According to USB-IF, three additional voltages can be used: "28V (above 100W), 36V (above 140W) and 48V (above 180W) joining previously defined 5V, 9V, 15V and 20V fixed voltages." 1

How Fast Is USB-C Type 2.1?

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USB-C type 2.1 supports up to a maximum of 40 Gb/s (4.8 GB/s) and is used by USB4 and Thunderbolt 4 data-transfer specifications.

In comparison, USB 3.1 gen 2 supports up to 10 Gb/s.

If USB-C type 2.1 reaches the max speed of 40 Gb/s, it's equivalent to transferring 1.5 hours of 4K video in 2 seconds.

While it can reach those speeds, the USB4 variant supports only 20 GB/s minimum. 40 Gb/s is optional to the manufacturer.

The Thunderbolt 4 variant will be guaranteed to reach 40 Gb/s.

Learn more about the differences between USB-C, USB4, and Thunderbolt 4 (TR).

Is USB-C Type 2.1 Backward Compatible?

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USB-C type 2.1 is backward compatible with other USB-C cables/ports, but using earlier cable/port versions will reduce speed and power.

For example, if you're using a USB-C 2.1 cable to charge your device with an earlier version USB-C port, it will use the lower data rates and voltages. Negotiations between devices and electronic labels in the cables tell the devices how much power they can handle.

In addition to that, adapters to USB 2.0 connections are the minimum version that's supported.

To be sure, check the label of each cable and device to determine if it's fully supported for your needs.

To prevent damage to your devices, make sure the cable is certified and meets the USB-C type 2.1 specification before using it.

How Do I Tell if a USB-C Cable Is the High Powered USB-C Type 2.1?

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USB-C Type 2.1 cables are marked to indicate whether they deliver the Standard Power Range (SPR) or both SPR and Extended Power Range (EPR).

According to the Power Delivery 3.1 announcement from USB-IF in early 2021, "Branding and marketing guidelines are being established and will include a new cable labeling solution to inform users of the power capability supported by Certified USB Type-C cables." 2

Considering the lack of proper labeling on past USB cables/ports, we can expect similar behavior from manufacturers who don't follow this updated specification; in particular, off-branded cables and devices are less likely to adhere to the specification.

It's best to rely on the packaging and documentation included with your cables and devices to determine what it supports and is rated for and buy from trusted sources.

Will the Increased Voltage of the USB-C Type 2.1 Create Arcing Damage?

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No, the USB-C type 2.1 cables should detect and discharge when the cable is disconnected, preventing any arcing damage.

The new specification of the USB-C type 2.1 specifies that the disconnected contacts can't reach 12 volts until it's at a safe distance.

Taking into account that everyone unplugs their device at different speeds, there's still some possible arcing after many times plugging/unplugging the wire. However, arcing mostly happens when a cable is unplugged very slowly.

The faster the cable is unplugged, the less chance there is for arcing damage. However, more precautions are now used to reduce the damage even when unplugging slowly, so there shouldn't be a need to worry unless the cable used isn't certified or doesn't meet the USB-C type 2.1 specification.

More stringent safety requirements are in place to handle the higher power rate of type 2.1. 3

The document provided by USB-IF mentions: "The goal of arcing mitigation is not necessarily to entirely prevent arcing but to prevent damage to the connector pins due to arcing that may still occur." 4

Examples of USB-C Arc Damage which USB-C Type 2.1 is mitigating Examples of USB-C Arc Damage which USB-C Type 2.1 is mitigating USB 3.0 Promoter Group

What Is the Difference Between USB-C, USB4, and Thunderbolt 4?

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USB-C is the type of physical connector with a long, rounded, symmetrical shape.

USB4 and Thunderbolt 4 are data transfer and manufacturing standards that use a USB-C connector.

USB Type-C (USB-C) Plug USB Type-C (USB-C) Plug USB 3.0 Promoter Group

USB4 and Thunderbolt 4 both use USB-C connection types and offer similar features.

All USB-C cables aren't the same, though, and not all support the functionality and speeds of USB4 or Thunderbolt 4 ports.

USB4 is backward compatible with previous USB-C cable/port versions, but using older cables/ports will reduce the data speeds and functionality.

While USB4 is capable of speeds of up to 40 Gb/s max, implementations are only required to reach speeds of 20 Gb/s.

Only the Thunderbolt 4 cable is guaranteed to reach 40 Gb/s, which would allow you to run two 4K displays at once, requiring minimum speeds of 32 Gb/s.

USB-C type 2.1 (announced May 2021) supports USB4 and Thunderbolt 4 functionality and maximum speeds of 40 Gb/s.

If it reaches that max speed, that's equivalent to transferring 1.5 hours of 4K video in 2 seconds.