The device, charger and cable must negotiate a compatible power profile before fast charging can begin. The actual charging speed depends on the capabilities shared by all three components, the charging protocol in use and the way heat is managed.
A charger does not simply force a high level of power into a device. The device communicates the power it can accept, the charger presents the profiles it can provide, and the cable must be capable of carrying the negotiated power safely.
“These are the voltage and current levels I can safely accept.”
“These are the power profiles I can provide.”
“I can safely carry the negotiated current and power.”
Three basic concepts are enough to understand charging technology: voltage (V), current (A) and power (W). Electrical power is calculated by multiplying voltage by current.
| Voltage / Current Profile | Calculation | Total Power | Typical Use Example |
|---|---|---|---|
| 5V / 1A | 5 × 1 | 5W | Basic charging |
| 5V / 2A | 5 × 2 | 10W | Standard USB charging |
| 5V / 3A | 5 × 3 | 15W | Basic USB-C power profile |
| 9V / 2A | 9 × 2 | 18W | Fast-charging range |
| 9V / 3A | 9 × 3 | 27W | Phone / tablet |
| 11V / 3A | 11 × 3 | 33W | Variable profile example |
| 12V / 3A | 12 × 3 | 36W | May vary by manufacturer |
| 15V / 3A | 15 × 3 | 45W | Tablet / lightweight laptop |
| 20V / 3.25A | 20 × 3.25 | 65W | Laptop |
| 20V / 5A | 20 × 5 | 100W | High-power USB-C |
| 28V / 5A | 28 × 5 | 140W | USB PD EPR |
| 36V / 5A | 36 × 5 | 180W | USB PD EPR |
| 48V / 5A | 48 × 5 | 240W | USB PD EPR upper range |
The voltage and current values shown here are examples. Supported profiles may vary depending on the device, charger, protocol and manufacturer.
These three technologies describe different ways of managing power delivery over USB-C. The key distinction is how precisely the output voltage can be selected or adjusted.
USB Power Delivery is a widely adopted charging standard for USB-C. The device and charger negotiate a fixed power profile that both support before power is delivered at that level.
Rather than relying only on fixed voltage levels, PPS allows the output voltage to be adjusted in fine steps within a defined range. This enables the charger to respond more precisely to the power requested by the device.
AVS provides adjustable voltage operation within newer USB Power Delivery implementations. It is particularly useful for finer power control at higher output levels.
The maximum wattage stated on a charger is the highest output the charger can provide under supported conditions; it does not mean that every connected device will draw that amount. For example, a phone that negotiates 9V / 3A may charge at around 27W, while a laptop connected to the same charger may negotiate 20V / 3.25A and draw close to 65W.
Some profiles, including 12V profiles, may vary between manufacturers and products. The actual profiles supported by a charger should therefore be confirmed from its technical specifications.
These terms refer to different parts of the charging ecosystem: GaN is a semiconductor technology, Quick Charge is a family of fast-charging technologies, and Qi is a standard for wireless power transfer.
GaN is not a charging protocol. It is a semiconductor technology used in the power-conversion circuitry inside a charger. Compared with conventional silicon-based designs, it can enable higher power density, smaller form factors and more efficient power conversion.
Quick Charge is a family of fast-charging technologies developed by Qualcomm. Different versions support different voltage, current and control methods, so available charging profiles can vary according to the device, charger and Quick Charge version in use.
Qi is a standard for wireless power transfer. Depending on the device and implementation, charging power may be offered at levels such as 5W, 7.5W, 10W, 15W or higher. Magnetic alignment can help position the device more accurately over the charging coil and maintain a consistent coupling position.
These are fast-charging technologies developed by individual manufacturers. A compatible charging mode can be used only when both the charger and the connected device support the relevant protocol. Voltage and current levels may vary according to the device model and the manufacturer-specific implementation.
A high-power charger cannot deliver its full capability if the cable is not designed to carry the required current and power safely. In that situation, the charging system may negotiate a lower power level.
High-power USB-C cables may contain an electronic identification chip known as an E-Marker. It communicates the cable’s supported current rating, power capability and certain connection characteristics to compatible devices.
To achieve the intended charging performance, the charger, device and cable must all support the required power profile.
As the battery approaches a higher state of charge, or as temperature increases, the device may deliberately reduce charging power to manage heat, safety and long-term battery health.
These values are examples only. The real charging curve may vary depending on the device, battery temperature, battery health, software and manufacturer.
The technology, standard, protocol, product and brand names mentioned on this page are used for information purposes only. USB, USB-C, USB Type-C, USB Power Delivery (USB PD), Quick Charge, Qi, Qi2 and other third-party names may be trademarks, registered trademarks or other intellectual property belonging to their respective owners. Unless explicitly stated otherwise, Gressu and Gressu Networks do not claim any partnership, sponsorship, representation or endorsement relationship with the owners of these brands or standards. Charging power, voltage, current, speed and compatibility values shown on this page are provided for general information and illustrative purposes. Actual performance may vary depending on the device, charger, cable, protocol version, software, battery condition, temperature and manufacturer implementation. Use of third-party logos, certification marks or compatibility symbols is subject to the licensing, certification and brand-use requirements of the respective rights holders.