What Is USB Power Delivery (PD)?

In the world of USB charging, USB Power Delivery (PD) has emerged as a powerful and versatile charging standard that allows devices to charge faster, more safely, and more efficiently. USB PD offers higher power levels than traditional USB charging, making it ideal for a wide range of devices, from smartphones to laptops. This article explains what USB Power Delivery is, how it works, and why it matters for today’s devices.

Understanding USB Power Delivery

USB Power Delivery (PD) is a charging standard introduced to provide higher power and greater flexibility for USB devices. Unlike earlier USB standards, which limited power to lower wattages, USB PD can deliver up to 100 watts (W) of power, making it suitable for power-intensive devices like laptops, tablets, and monitors.

Key Benefits of USB Power Delivery

  • Faster Charging: USB PD can dynamically adjust the power output, allowing compatible devices to charge faster.
  • Bidirectional Power: USB PD can deliver power in both directions. For example, a USB PD power bank could charge a smartphone, and the same smartphone could also charge the power bank if needed.
  • Standardised Compatibility: USB PD is a universal standard that works across multiple brands and devices, making it easier to use a single charger for different devices.

How USB Power Delivery Works

USB PD works by enabling dynamic power negotiation between the charger and the connected device. Here’s how it functions:

  1. Initial Connection: When a USB PD-compatible device is connected to a PD charger, the two begin communicating to determine the appropriate power level.
  2. Power Negotiation: The device communicates its power needs to the charger, and the charger adjusts its output to meet those requirements. This process allows devices to charge at their optimal speed without exceeding safe power levels.
  3. Adaptive Power Adjustment: As the device's battery level changes, the charger adjusts its power output to prevent overheating and to optimise charging. Once the device reaches full charge, USB PD reduces power to maintain the battery safely.

Power Levels in USB PD

USB PD offers various power levels, typically based on voltage and current combinations. These levels include:

  • 15 W (5 V / 3 A): Suitable for smartphones, tablets, and smaller devices like Bluetooth accessories and wearables.
  • 27 W (9 V / 3 A): Provides faster charging for smartphones and tablets, ideal for devices that support quick charging.
  • 45 W (15 V / 3 A): Compatible with tablets and some lower-powered laptops; a common choice for larger tablets or Chromebooks.
  • 60 W (20 V / 3 A): Powers medium-powered laptops and larger tablets, suitable for devices like Ultrabooks and high-end tablets with greater energy needs.
  • 100 W (20 V / 5 A): Designed for power-hungry laptops, monitors, and even some desktop computers, enabling full-speed charging for high-performance laptops.
  • 140 W (28 V / 5 A): A new power level aimed at high-performance devices like gaming laptops and advanced workstations that require more than 100 W.
  • 180 W (36 V / 5 A): Another new standard suited for professional-grade laptops and demanding workstations, providing enough power for heavy applications.
  • 240 W (48 V / 5 A): The highest power level available under USB PD, aimed at power-intensive devices such as gaming laptops, high-resolution monitors, and portable desktops that require maximum power delivery.

These power levels allow USB PD to meet the unique power requirements of various devices, adjusting automatically to ensure safe and efficient charging.