USB PD (Power Delivery) is an advanced, fast-charging standard that supports various power requirements over a USB connection. Its predecessor, USB (Universal Serial Bus), was a wondrous invention in the late 1990s and revolutionized how we connected devices to our computers. Before that, we had various serial and parallel connections along with proprietary options.
USB introduced a fixed 5V power supply for peripherals, allowing companies to design around this power requirement. But as time went on, devices traditionally charged via a DC barrel jack moved to USB, and those devices started requiring more power or introducing proprietary protocols. This is where USB PD (Power Delivery) comes in. The first version of USB PD was designed for older USB-A devices; it wasn’t until USB PD 2.0 that USB-C became the dominant interface.
The USB C PD Specification
The key feature of USB-PD is smart power negotiation. The device and the charger communicate with each other and establish the correct power requirements without user intervention.
The specifications for USB-C PD have evolved over the years. We are currently at USB-PD 3.2, which introduced new branding/terminology. The specification defines communication standards that enable the device to report its power capabilities. The latest version of this protocol, the Power Supply Block (PSB), was PSB-P3.1 in 2021, and that standard is backward compatible with previous versions.
As a result of the spec, I can charge my smartphone at 18W and my Lenovo X390 at 65W from the same USB PD charger; there is no longer any need to carry multiple chargers. Even Apple devices, which have long used proprietary connectors, are moving to USB-C due to EU regulatory requirements.
Let's take a look at the specs.
Swipe to scroll horizontally The USB PD Specifications Header Cell - Column 0 USB PD 1.0 USB PD 2.0 USB PD 3.0 USB PD 3.1 Release 2012 2014 2015 2021 Max Power 60W 100W 100W 240W USB Connector A, B, Micro B C (Introduced) C C Output 5V 2A 12V 1.5A 12V 3A 20V 3A 5V 3A 9V 3A 15V 3A 20V 2.25A 20V 3A 20V 5A 5V 3A 9V 3A 15V 3A 20V 2.25A 20V 3A 20V 5A PPS 3.3V - 5.9V 3A 3.3 - 11V 3A 3.3 - 16V 3A 3.3 - 21V 3A 3.3 - 21V 5A 5V 3A 9V 3A 15V 3A 20V 3A 20V 5A PPS 3.3V - 5.9V 3A 3.3 - 11V 3A 3.3 - 16V 3A 3.3 - 21V 3A 3.3 - 21V 5A AVS 15 - 28V 5A 15 - 36V 5A 15 - 48V 5A
PPS: Programmable Power Supply, introduced in USB PD 3.0 that enables a device to dynamically adjust voltage and current for efficient charging.
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