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GaN chargers explained
GaN chargers are the reason a 100 W charger can now be the size of an old 20 W phone plug. If you carry a laptop, phone and earbuds, one good GaN charger can replace every brick in your bag. Here is what the letters mean and how to choose one.
What GaN is
GaN stands for gallium nitride, a semiconductor material used in place of silicon for the transistors that switch power inside a charger. GaN transistors can switch faster and waste less energy as heat. Less heat means the parts can be packed more closely, and faster switching allows smaller transformers and capacitors. The result is a smaller, lighter charger that runs cooler at the same output.
GaN itself does not make your devices charge faster. Charging speed is decided by the charger's wattage and the USB Power Delivery standard that both ends agree on.
How many watts do you need?
Add up what you want to charge at the same time, using each device's maximum charging rate:
| Device | Typical maximum |
|---|---|
| Earbuds | 5 W or less |
| Smartphone | 20 to 45 W |
| Tablet | 20 to 45 W |
| Ultrabook laptop | 30 to 65 W |
| Larger laptop | 90 to 140 W |
A 65 W two- or three-port charger suits most people with a thin laptop and a phone. A 100 W model covers a larger laptop plus a phone. Above that, chargers get heavier and are mainly useful for power-hungry laptops.
Power sharing: the small print
A multi-port charger's headline wattage is the total, not per port. When you plug in a second device, the charger divides its output. For example, a 65 W charger might give 65 W to one port, but 45 W plus 20 W when two devices are connected. The split is usually printed on the charger or listed in the manual.
When you plug or unplug a device, many chargers briefly cut power to all ports while they renegotiate. That is normal, but it can interrupt an external drive or a monitor powered from the same charger.
What else to check
- Port types. USB-C ports for laptops and modern phones; a USB-A port is useful for older cables and accessories, but usually charges slowly.
- Folding pins and, for travel, interchangeable plug heads.
- Safety certifications for your region (for example CE and UKCA marks in Europe and the UK, UL listing in North America). Very cheap unbranded chargers sometimes skip proper protection circuits.
- Programmable Power Supply (PPS) support if you have a recent Samsung phone and want its fastest charging mode.
- Heat. A GaN charger can feel warm at full load; that is normal. Uncomfortably hot to touch is not.
Is it safe to charge a phone from a big laptop charger?
Yes. A USB-C Power Delivery charger only supplies what the device asks for. A phone that accepts 20 W gets 20 W from a 100 W charger. The device, not the charger, decides how much power it takes.
Do not forget the cable
A 100 W charger needs a cable rated for 100 W (5 A) to deliver more than 60 W. Most cables sold with phones are 3 A, which caps the power at 60 W. See why USB-C cables are not all the same.
A single 65 W GaN charger and two good cables is the backbone of a light one-bag tech kit.