USB Power Delivery explained: What you need to know about ubiquitous charging

Fast charging is a godsend when our gadgets run low on juice. However, there are numerous fast charging standards in existence today, making it difficult to pick the right charger for your smartphone, laptop, or even external monitor. Furthermore, while most gadgets historically shipped with an adapter in the box, many brands are now asking you to bring your own. Luckily, USB Power Delivery (USB PD) is a universal charging specification that allows you to sidestep the fragmented phone charger market altogether.

Here’s everything that you need to know about USB Power Delivery and what it means for your gadgets.

USB Power Delivery: What you need to know

USB Power Delivery is a common fast-charging standard that can be implemented in all USB-powered gadgets. USB PD has actually been around since 2012, around the same time that the USB-C port was unveiled. Prior to that, the only universal option was the (significantly slower) USB Battery Charging specification.

The humble USB-C port is pretty complicated and can support several different levels of charging. And that’s before manufacturers add proprietary capabilities on top of that.

To start with, all USB ports support a very basic level of charging at just 5V and up to 500mA, with more modern ports supporting 5V and 900mA of current. This is based on legacy support and is very slow to charge all but most low-power gadgets. USB-C ports can be configured with 5V 1.5A and 3A for up to 15W of power, which is a bit quicker but still rather slow compared to other fast-charging standards.

USB Power Delivery is much more powerful, supporting up to 240W of power to charge up even the most demanding gadgets such as laptops. It’s also safer, as gadgets and chargers communicate with each other over the USB cable to confirm the optimal charging power level. This handshaking approach supports voltage steps at 5V, 9V, 15V, 20V, and beyond for power outputs ranging from 0.5W to 240W.

The newer USB Power Delivery Programmable Power Supply (USB PD PPS) standard supports configurable voltages too, enabling more optimal charging. If two devices fail to communicate a suitable power rule, USB Power Delivery will default to the next power option supported by the relevant USB protocol, such as USB-C 1.5A.

USB Power Delivery is now commonly used to fast-charge smartphones, laptops, and other gadgets. Examples include the entire line-up of Google Pixel phones, Apple’s iPhone and MacBooks. Even Samsung’s Super Fast Charging is based on USB PD PPS.

A huge range of other smartphones support the standard too, often in addition to their faster proprietary standards. Many OnePlus smartphones, for example, support between 18 to 27W charging over USB PD. That’s in addition to the company’s own Warp Charge or Oppo’s SuperVOOC technology.

Is a USB type-C to type-C cable necessary for Power Delivery?

While the first revision of Power Delivery did technically work with standard USB Type-A ports, very few devices supported this functionality. These days, you’ll find most devices that rely on Power Delivery use USB Type-C or USB-C on both ends. This is also why most smartphones these days ship with USB-C to USB-C cables in the box. You can still use a Type-A to USB-C cable for charging but expect slower speeds.

USB Power Delivery versions compared

With USB Power Delivery now in its third revision, the standard is broken down into devices with slightly different capabilities. Although modern versions of the standard are backward compatible with older gadgets and chargers.

USB PD 1.0 was a little more basic than the modern version. It simply offered six fixed power profiles for different device categories. This version supports 10W (5V, 2A), 18W (12V, 1.5A), 36W (12V, 3A), 60W (12V, 5A), 60W (20V, 3A), and 100W (20V, 5A) of power exclusively. That’s OK, but not exactly flexible for a wide range of gadgets, including small smartphone batteries that prefer lower voltage charging.

The more modern USB Power Delivery 2.0 and 3.0 variations drop fixed profiles in favor of more flexible power rules. These rules keep fixed voltage brackets but allow for a wider range of negotiated current levels. The end result is a standard that’s better suited to a wide range of devices. USB Power Delivery 3.0 also extends the communication protocol to support features like battery condition, enhanced security, and fast role swapping.

The majority of modern smartphones make use of the USB Power Delivery 2.0 and 3.0 specification. 25 to 45W of power is quite typical for smartphones, while today’s laptops pull around as much as 100W and beyond. The latest 3.1 revision will eventually bring about devices with 140W, 180W, and 240W charging, although we haven’t seen widespread adoption just yet.

USB PD Programmable Power Supply (PPS) explained

Despite improvements with USB Power Delivery 2.0 and 3.0, they’re still not entirely suited to the flexible requirements of very fast charging. Battery charging speed is sensitive to specific voltages and this changes depending on the battery’s current charge. The 5V, 9V, 15V, and 20V set voltages in the standard specification aren’t ideal for optimal fast charging.

The USB Power Delivery 3.0 revision released in 2018 also introduced the Programmable Power Supply protocol into the standard. USB PD PSS is much more flexible, allowing for configurable voltage levels at very small 20mV granular increments. Combined with device-to-charger communication and voltage-control charging algorithms, the ideal voltage can be negotiated and even changed during charging. This makes USB PD PPS far better suited to fast charging than the standard USB PD protocol.

As the newer part of the standard, support for USB PD PPS is limited to just a handful of gadgets and charging accessories in 2021. Support is starting to grow, particularly in the charger market, but the latest specification is leading to a few headaches for consumers. For example, Samsung’s Galaxy S24 series can only be fast-charged at their full 45W of power using USB PD PPS chargers. Otherwise, consumers are stuck with a slower 18W when using standard USB PD. The same applies to Google’s Pixel series of smartphones, although the latest Pixel 9 Pro XL exposes the inconsistent state of USB PD charging. It requires 18V at 2A to charge, instead of the more widely accepted 9V.

How fast is USB PD charging?

Given the variable nature of USB PD charging and the wide range of battery capacities, it’s impossible to give a precise speed for the standard. Very broadly speaking though, large battery capacity phones charge to full using 18W USB Power Delivery in a little over an hour. Large-capacity laptops using 65W charging can take an hour or two.

Unlike laptops, smartphones generally don’t like to use high voltages to charge their batteries. Typically, smartphone fast charging uses 5V or 9V and high currents to charge up the battery. For example, OnePlus’ now-older 65W charging tech uses 10V and 6.5A charging and HUAWEI’s 40W option uses a similar 10V and 4A. Keep in mind that both of these are proprietary technologies.

9V is the closest USB PD voltage setting, which is capped at a much slower 27W of maximum power. Most USB Power Delivery smartphones we’ve seen don’t actually use the full 3A either, capping their power at 18-20W. That said, we’ve seen manufacturers like Google, Motorola, and Samsung slowly go beyond that with USB PD PPS, achieving 25W to 45W fast charging.

Proprietary technologies are pushing the boundaries even further, with OPPO teasing 240W and Xiaomi already offering 120W charging. That said, there are diminishing returns in terms of power consumption versus charge time anyway. Around 45W is plenty to charge a smartphone quickly enough.

Consumer convenience and the ecological argument

While charging speed is an important factor in the design of USB Power Delivery, and PPS in particular, it’s not the primary design goal. USB PD was created as a single standard to power a wide range of USB gadgets. Thereby reducing the need for proprietary ports, connectors, and plugs.

First and foremost, this should make it much easier for consumers to just plug and charge. E-waste from old chargers and cables is a growing problem, not just for landfills but as a drain on precious metals and other finite resources. There are strong environmental reasons for consumers and manufacturers to embrace a unified charging technology like USB Power Delivery.

Smartphone brands removing charging bricks from the box may be a controversial decision today, particularly as consumers don’t necessarily own a compatible USB PD PPS charger. But in the long term, we might not pay a second thought to the lack of bundled chargers as all our gadgets charge quickly from plugs we already own. And if you want to buy one charger for multiple devices, you can always get a multi-port USB wall adapter. That’s the theory anyway.