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USB-C charging with 140 watts: compatibility & technical background

Introduction

Some of our laptops support 140 watts via USB-C, however not over the public USB-PD 3.1 protocol, but rather with an extension of the older USB-PD 3.0 standard.

What is the difference between these two approaches?

Overview:

  USB-PD 3.1 (public) Extension of USB-PD 3.0 (proprietary)
Power 140 watts 140 watt
Maximum voltage 28 volts 20 volts
Maximum current 5 amps 7 amps

The basic formula:

Power (W) = voltage (V) × current (A)

The key difference between the two approaches lies in how the 140 watts are composed of voltage and current.

  • USB-PD 3.1 is always limited to 5 amps, even in the higher ranges from 180 to 240 watts.
  • USB-PD 3.1 must therefore increase the voltage to achieve the higher power output from the 5 amps limit.
  • With USB-PD 3.0, on the other hand, the voltage is capped at 20 volts. With USB-PD 3.0, increasing power requires increasing the current instead.

Our extension of USB-PD 3.0 is implemented in the USB-C handshake protocol as a 'Vendor-defined message' (VDM).

Affected models

Support for 140 watts via USB-C with 20 volts (20V×7A) applies to the following models:

  • XMG EVO 15 - E25
  • XMG CORE 15 - M25
  • XMG PRO 16 - E25
  • XMG NEO 16 - E25
  • XMG NEO 16 - A25
  • Further models in planning

What are the advantages and disadvantages of these different solutions?

Let us put these implementations side-by-side:

USB-PD 3.1 (public) Extension of USB-PD 3.0 (proprietary)

If the current remains constant, there is no need to change the design of the cables in any significant way. Higher currents would require stronger wires/conductors and therefore thicker cables. The USB-PD 3.1 standard is therefore designed to change the cables as little as possible.

 

This reduces the risk of overheating when using older (weaker cables) with newer chargers or docking stations, thereby increasing compatibility in a fragmented market environment.

With an extension of the USB-PD 3.0 standard, however, it is the voltage that remains constant. This simplifies implementation in the laptop itself, as it can be carried out using proven components that are also used for power input with conventional AC adapters with barrel plugs.

 

The implementation of multiple voltage sources in laptops would mean considerable additional effort, also in terms of the space available on the motherboard and the conversion losses and additional heat output generated in the laptop from a conversion from 28 volts.

Summary:

  • USB-PD 3.1 is optimised to work safely (without the risk of cable overheating) with as many market participants as possible and in combination with cables from different manufacturers. Additional costs and conversion losses arise mainly on the 'host' side, i.e. in the end device such as the laptop.
  • 140 W over 20V×7A, on the other hand, is optimised for efficiency, cost savings and space savings in the laptop. Because the 1.5 m cable is permanently attached to the AC adapter in our 140 W USB-C charger, there is no risk of using unknown or substandard cables. The 20-volt limit aligns with industry standards used in laptops for the past 30 years, which makes it much easier to use with normal barrel plug AC adapters.

Why did we decide on the 20-volts solution?

As previously outlined, the 20-volt solution is overall more efficient for laptops. We would like to explain this further in more detail:

  • The motherboard design in our laptops is based on a 20-volt architecture, which is used for both USB-C and the regular AC adapter. Support for 28 volts would require additional voltage regulators, which would take up more space and generate additional waste heat (conversion loss) in the laptop during operation.
  • By using a uniform voltage for both power sources, the existing infrastructure can be used up to the maximum power supply configuration of 420 watts (20V×14A) in the XMG NEO 16 (2025) without having to provide separate components for 28 volts. This reduces validation overhead and improves overall system reliability and efficiency.
  • Available space is limited, especially in the power supply area and between the CPU and the USB-C port, which, depending on the CPU platform, must also provide Thunderbolt or USB4 connectivity. Additional components for 28-volt support would affect the layout and features of the rear I/O ports of the affected laptop models. See this picture for reference.

The same reasons apply to all XMG EVO models (from 2025 onwards), as they use mainboard layouts compatible with XMG CORE, FUSION, PRO and NEO of the same generation.

Compatible chargers

The above-mentioned models can only support 140 watts via USB-C with chargers that explicitly support 20V×7A.

Currently, there is only one model supported by us:

  • FSP150-APDBR01 (shop link will follow shortly)

This original adapter from FSP is already included in the box with XMG EVO 14 and XMG EVO 15 with AMD Ryzen AI 300 series. For other models, it can be ordered from our online shop as a travel charger.

In addition to the additional 20V×7A mode, it is also backwards compatible with all common USB-PD 3.0 standards. It can therefore also be used to charge any USB-C devices (laptops, tablets, mobile phones, game consoles, Bluetooth speakers, etc.). This makes the FSP150-APDBR01 a strong option for users seeking a universal USB-C charger.

Safety reserve for power surge and peaks

The AC adapter we recommend is also specially designed to absorb power spikes that may not be provided or guaranteed by conventional chargers with USB-PD 3.1. This is particularly relevant when used in gaming laptops, as dedicated graphics cards tend to cause very brief and unpredictable power spikes in the millisecond or even nanosecond range. For more information, please refer to this FAQ article:

The VDM (vendor-defined message) communication between the FSP150-APDBR01 and our compatible laptops therefore not only handles the basic availability of 20 volts and 7 amps, but also negotiates the necessary headroom for these power peaks.

Is there anything I need to consider when selecting USB-C plugs or cables?

No. The FSP150-APDBR01 charger we recommend already has a permanently installed 1.5-meter cable. The cable and plug are validated for continuous operation at 7.5 amps and also support peak loads of up to 12.6 amps.

The design decision to support 140 watts only via a 20V×7A solution has no effect on the operation of other USB/Thunderbolt peripherals or on the use of older AC adapters with up to 100 watts of power.

Other brands

Lenovo has been using a similar solution on certain laptop models since the beginning of 2023 (see Lenovo chargers LA135 and LA140), presumably for the same reasons as us. We will not test whether these Lenovo chargers are compatible with our laptops (i.e. whether they can also charge at up to 140 watts), as we already have a compatible, validated and ultra-portable charger in our FSP150-APDBR01. Even if these 20-volt enabled 3rd party brand charge at 140 watts, it is uncertain whether they have the same safety reserve as our validated AC adapter, which is why we do not recommend using these Lenovo AC adapters.

Docking stations with 20V×7A are not on the roadmap

We have discussed this matter with various docking station makers. We currently do not see any docking station on any roadmap that would be able to implement our extensions with 140 watts over the USB-PD 3.0 protocol.

Even if a docking station maker would venture to support this power level, it would be difficult to guarantee full compatibility and stability with the aforementioned power surges and spikes, especially in combination with a docking station that is fully equipped with peripherals and thus would itself consume quite a lot of power.

Any 3rd party docking station that advertises 140 watts of USB-C power delivery (or more) would only operate with 100 watts on our laptops. Operation with 100 watts is absolutely enough for an ultrabook series such as XMG EVO and can also charge and operate more high-powered gaming laptops or workstations.

For any laptop with dedicated GPU, we still recommend to connect our original charger (usually between 250 and 420 watts, depending on the laptop configuration) to the laptop, in tandem with the docking station’s USB-C cable.

Incompatible devices are downgraded to 100 watts

Standard docking stations and chargers that deliver their 140 watts via USB-PD 3.1 with 28 volts (28V×5A) cannot be used at full power. Instead, they downgrade to the lower (but still usable) 100 watts standard (20V×5A).

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