Reference Guide

Charging Glossary

Plain-English definitions for every charging term you'll encounter — GaN, USB-PD, PPS, UL, and more. Authoritative reference used by consumers and professionals alike.

20 terms defined. Use Ctrl+F (or ⌘+F on Mac) to find a specific term. All definitions are reviewed by our charging technology experts.

GaN (Gallium Nitride): A semiconductor material used in next-generation charger circuits. GaN transistors switch faster and waste less energy as heat than traditional silicon, enabling smaller, cooler, and more efficient chargers.
USB-C: A reversible connector standard. USB-C describes the physical shape only — not the speed or power. A USB-C port can carry anything from basic 5W charging to 240W USB4 power, depending on the cable and device.
USB Power Delivery (USB-PD): The universal fast charging standard. Supported by iPhones (8 and later), MacBooks, iPads, most Android flagships, and laptops. USB-PD allows the charger and device to negotiate the optimal voltage and current — up to 240W with the latest spec.
PPS (Programmable Power Supply): An extension of USB-PD that allows finer voltage and current control in small steps (e.g. 3.3V–11V at 1mV increments). Supported by Samsung Galaxy, Google Pixel, and select other Android devices for faster, cooler charging.
Quick Charge (QC): Qualcomm's proprietary fast charging standard, built into phones and tablets with Snapdragon processors. QC 4+ is backwards compatible with USB-PD/PPS. Older QC 2.0/3.0 use USB-A and are being phased out.
Watt (W): The unit of charging power. Watts = Volts × Amps. A 65W charger can deliver 65 watts to a connected device — but only if both the charger and device support the same protocol.
Volt (V): The electrical potential driving the charge. USB-PD dynamically adjusts voltage (typically 5V, 9V, 15V, 20V) based on what the device requests.
Ampere / Amp (A): The flow rate of electricity. Higher amps mean more current — which increases wattage. A 5V/3A output delivers 15W; a 20V/5A output delivers 100W.
Multi-port charger: A charger with two or more ports. Quality GaN multi-port chargers use intelligent power sharing, dynamically redistributing wattage based on what's plugged in. Cheap multi-port chargers split power evenly regardless of need.
Charging brick / wall charger: The AC adapter that plugs into the wall. Not to be confused with the cable. The charger converts mains AC power to DC power for your device.
Power bank / portable charger: A battery pack used to charge devices on the go. Capacity is measured in mAh (milliamp-hours). A 10,000mAh power bank can fully charge most phones 2–3 times.
mAh (milliamp-hour): Measure of energy capacity in batteries and power banks. Higher mAh = more charges. Most phone batteries are 3,000–5,000mAh; most laptops are 50,000–100,000mAh.
FCC Certification: Federal Communications Commission certification required for electronic devices sold in the USA. FCC certification confirms the device meets US radio frequency and electromagnetic interference standards.
UL Certification: Underwriters Laboratories (UL) is a US safety certification body. UL-certified chargers have been independently tested for fire, shock, and overheating safety. Look for the UL mark on any charger you buy.
Over-voltage protection (OVP): A safety feature that stops the charger from delivering excess voltage that could damage connected devices. All quality chargers include OVP.
Over-current protection (OCP): Prevents the charger from drawing too much current, protecting both the device and the charger from damage.
Thermal cutoff: A safety circuit that cuts power if the charger exceeds a safe temperature threshold. Prevents overheating, fire risk, and device damage.
USB4 / Thunderbolt 4: The latest USB connection standard. USB4 cables support up to 240W charging alongside 40Gbps data transfer. Thunderbolt 4 is Intel's implementation of USB4 with additional performance requirements.
Charging efficiency: The percentage of input power that makes it into the device vs. lost as heat. GaN chargers typically achieve 95%+ efficiency; older silicon chargers are 85–90%.
Passthrough charging: A power bank feature that allows simultaneous input (charging the bank) and output (charging a device). Quality passthrough charging minimises the efficiency loss from charging both at once.