6 things you need to know to untangle the USB Power Delivery charging mess

One of the most positive tech developments of this decade has been the mass adoption of USB-C over the old micro-USB, USB-A, and other lesser-used gadget ports. Whether you’re powering your earbuds, smartphone, or laptop, one little port can charge them all — at least in theory. Unfortunately, if you’ve spent any time trying to charge all these gadgets optimally with even the best third-party adapters, you’ll doubtless be aware of the labyrinth of charging standards and protocols that must be navigated to have everything play nicely together.

At the heart of modern charging is USB Power Delivery (USB PD), the USB Implementers Forum’s official fast charging standard that can supply more power than a USB-C port’s basic capabilities. Apple, Google, and Samsung smartphones, as well as virtually every other handset and laptop on the market today, support USB Power Delivery in one form or another.

Like any technology standard, the trick is that the charger and device must support the same capabilities and power levels. This means you’ll need 100W USB Power Delivery on your laptop and charger, for example. Thankfully, this is easy enough to obtain, but the USB Power Delivery landscape is complicated by its various revisions (1,0, 2.0, 3.0, 3.1, and 3.2) and optional protocol levels.

To help us understand this charging quagmire, I’ll explain everything you need to know about USB Power Delivery.

USB Power Delivery has actually been around since before USB-C, but it only really took off once the universal port hit the scene. At its core, USB PD does two things: it lets devices agree on how much power to deliver and it defines the current and voltage at which that power can be supplied.

The first part — the handshake — happens automatically whenever two PD-capable devices are connected. Using the USB data lines, the charger and device quickly exchange information about what they can provide or accept. In some cases, this handshake repeats as the charging session goes on, so the device always shares the most efficient power level.

The second part — the power delivery itself — is what’s important to us end users. A regular USB-C port can deliver up to 15W (5V at 0.5A, 0.9A, 1.5A, or 3A, depending on the port). USB PD increases this to 100W using a series of set voltages: 5V, 9V, 15V, and 20V with up to 5A of current, for a maximum of 100W. This makes it suitable for lower voltage headphones, medium voltage handsets, and high voltage laptop batteries, all from one power source.

For example, your smartphone might require 9V, 3A for 27W charging, while your laptop asks for 20V, 5A to charge at 100W from the same plug. It really is as simple as that, at least in the beginning.

In 2021, USB PD 3.1 introduced the concept of Standard Power Range (SPR) and Extended Power Range (EPR) devices. The latter can reach 240W through additional fixed voltages at 28V, 36V, and 48V. EPR is far beyond the needs of smartphones but is built to support large 8K monitors, powerful workstations, industrial applications, and other demanding use cases that previously relied on barrel connectors.

While these fixed power levels are useful, they’re not super efficient, given the changing nature of battery voltages as a device charges up. As such, USB Power Delivery has also been updated with two significant optional add-ons designed to improve efficiency and reduce heat — namely, Programmable Power Supply (PPS) in version 3.0 and Adjustable Voltage Supply (AVS) in the 3.1 and 3.2 revision.

• USB-C without PD: 5V @ 0.5A–3A (max 15W)
• USB PD (SPR): 5V, 9V, 15V, 20V up to 100W
• USB PD (EPR): adds 28V, 36V, 48V up to 240W
• USB PD PPS: variable voltage in small 20mV steps up to 100W
• USB PD AVS: configurable voltage in 100mV steps up to 240W

If you’re fast-charging an Android phone, you’ll likely want to check that your adapter is compliant with USB PD PPS, which was introduced as an optional extension in USB PD 3.0. While PPS remains limited to 5A and 100W, it introduces real-time, fine voltage and current control down to tiny 20mV and 50mA increments. This allows PPS to scale to values previously impossible to reach by regular Power Delivery — even going as low as 5V and, in some cases, down to 3.3V with lower current options available as well.

This flexible voltage control allows PPS to track Li-ion and Li-poly battery voltage and current demands in real time, making it far more efficient than regular PD. In fact, it can even bypass a phone’s internal regulating components, allowing the plug to charge the battery directly, resulting in far less heat generation and even greater efficiency. Without PPS, fixed voltages can lead to higher heat and slower charge once the battery is nearly full.

When it comes to charging adapters, PPS comes in two major varieties: 5V-16V and 5V-21V support. The latter is increasingly used by higher-power Android smartphones, such as the Google Pixel Pro XL models and Xiaomi 15 Ultra.

Finally, it’s worth reiterating that PPS is optional — not every PD adapter supports it, and not every device can take advantage of it. That’s why some phones only optimally fast charge with PPS-capable chargers. But if there’s a silver lining, your device will always fall back to regular PD fixed voltages, usually charging at 15–18W on typical smartphones.

If you’ve been eyeballing the new iPhone 17 series, you’ll have noticed that they finally support faster 40W charging courtesy of the USB PD AVS protocol. AVS has been around for a little while; it first appeared in 2021’s PD 3.1 specification to support EPR at up to 240W between 15V and 48V. However, it became mandatory for some SPR devices in version 3.2. AVS shares some ideas with PPS, but the two are certainly not interchangeable.

Like PPS, AVS offers adjustable voltage steps, though in 100 mV increments rather than PPS’s 20 mV, so not quite as fine-grained, and AVS’s lowest voltage is only 9V. While PPS is designed for real-time battery tracking and dynamic power adjustments, AVS should be considered more of a refinement of regular USB PD: it allows for more accurate one-time or intermittent voltage negotiation rather than continuous real-time adjustments for optimal fast charging.

As of USB PD’s 3.2 specification, gadgets that request 27W of power or greater must now support AVS, although Extended Power Range devices are exempt. Again, the aim is to improve the charging efficiency of higher-power devices, produce less heat, and improve long-term battery health. AVS also extends up to 240W, with much higher voltage capabilities than PPS. As for which is best suited to fast-charging a phone or laptop, PPS is the far more flexible and efficient option, but AVS is simpler to implement and supports even higher power levels for laptops and monitors.

Currently, adoption is limited: very few wall chargers or power banks support AVS. The standard was announced for gadget-level SPR in 2023, and the iPhone 17 series is the first smartphone to implement it. As such, you’ll have to buy a new charger to support it, which really undermines many of the e-waste promises that USB-C touted in its early years. Thankfully, regular USB PD remains a fallback option in cases where AVS isn’t available.

USB Power Delivery has undergone significant changes since its early mission to help power up and unify USB-C fast charging. Support has grown to power even more demanding devices, AVS has improved efficiency, and PPS has removed the need for priority fast charging standards that previously consumed the smartphone ecosystem.

While those improvements are welcome in isolation, the fractures within this supposedly unifying standard have made it more complicated than it should be for consumers to effortlessly pick out the right charger for all their gadgets. Matching power levels is already a significant ask for some, but even the most astute will struggle to understand the various AVS and PPS spin-offs, and neither are they helped by the lack of specs listed on many gadgets and power accessories.

While USB Power Delivery perhaps initially helped tackle consumer confusion and the world’s growing charger and cable e-waste problem, I’m not sure that today’s state of affairs really helped all that much in the long run. Hopefully, the USB-IF finally views its charging standard as universally useful enough to hit pause on the revisions for a few years, allowing the tech ecosystem to standardize so that consumers can finally reap all of the long promised benefits.