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01USB-C PD, minus the jargon
USB Power Delivery is the agreement system that lets a USB-C charger send more than the basic 5 volts. Your phone asks for what it can safely handle, the charger confirms what it can supply, and charging speeds up only after both sides agree.
Old USB chargers were dumb. They put out 5V and a little current, and the phone took what it could. That's fine for a 5W cube, but it caps out quickly. To push 20W, 30W or 60W through a thin cable, you need a higher voltage, and you can't just send 20V into any device that's plugged in. PD solves that with a short digital conversation over the USB-C cable before the power goes up.
Watts = volts × ampsA 9V, 3A PD setting is 27W. A 20V, 5A setting is 100W. Same cable shape, very different power.
PD is published by the USB Implementers Forum (USB-IF), the group behind the USB standard itself. It isn't tied to one phone brand, which is why a single USB-C PD charger can serve every phone in the house.
02How the PD handshake works
All of this happens in a fraction of a second after you plug in. You'll never see it, but it explains why the same charger behaves differently with different phones.
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Plug in at 5V
Every USB-C connection starts at plain 5V. If the phone or charger doesn't speak PD, it stays there, which is why an older device still charges, just slowly.
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The charger lists what it can do
A PD charger sends its menu of power options, for example 5V, 9V, 15V and 20V, each with a maximum current.
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The phone picks one
The phone requests the option that suits its battery and temperature right now. A phone that wants about 20W might ask for 9V at around 2.2A.
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The charger switches over
Only after the request is accepted does the voltage rise. If anything goes wrong, it drops back to 5V.
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They keep renegotiating
As the battery fills or warms up, the phone asks for less. That's why charging slows after about 80% even on a big charger.
The phone sets the pace. A 65W PD charger will charge a phone that wants 20W at about 20W. More on that in can I use a higher watt charger.
03PD voltage levels and wattages
PD uses a short list of fixed voltages. The current tops out at 3A on a normal USB-C cable and 5A on a cable with an e-marker chip, which is why cable rating matters at the high end.
| PD level | Max power | Cable needed | Typical use |
|---|---|---|---|
| 5V up to 3A | 15W | Any USB-C | Earbuds, watches, slow phone charging |
| 9V up to 3A | 27W | Any USB-C | Most phone fast charging |
| 15V up to 3A | 45W | Any USB-C | Tablets, small laptops |
| 20V up to 3A | 60W | Any USB-C (60W rated) | Laptops |
| 20V up to 5A | 100W | 5A e-marked cable (100W rated) | Bigger laptops |
| 28V, 36V, 48V at 5A (PD 3.1 EPR) | 140W, 180W, 240W | 240W-rated EPR cable | High-power laptops |
For a phone, the useful band is roughly 20W to 45W, plus the 60W that the newest Galaxy Ultra can use. A 100W cable is the safe default when you buy a spare, because it's rated for 5A and won't be the bottleneck later. Our USB-C cable types guide covers the differences.
04PD, PPS and Quick Charge: how they differ
You'll see three names on charger boxes. They're related but not the same, and the difference decides whether a Galaxy gets its top speed.
USB PD (fixed voltages)
- Set steps: 5V, 9V, 15V, 20V
- Standard on almost every USB-C charger
- All an iPhone needs to fast charge
PD with PPS
- Part of PD 3.0, adds fine voltage steps
- Required for Samsung Super Fast Charging
- Still works as plain PD for everything else
Qualcomm Quick Charge
- Qualcomm's own protocol, often on USB-A
- Newer versions overlap with PD
- Not needed for current flagship phones
PPS (Programmable Power Supply) lets the phone ask for voltage in tiny increments instead of jumping between fixed steps. That keeps more of the heat in the charger and out of the phone. The full story is in what is PPS charging, and USB PD vs Quick Charge compares the two big protocols.
05Which phones fast charge over PD
- iPhone: every model from iPhone 8 onward fast charges over USB PD. Apple recommends a 20W or higher USB-C adapter. iPhone 15 and later plug in with USB-C directly; older models need a USB-C to Lightning cable.
- Samsung Galaxy: Super Fast Charging runs over PD with PPS. A plain PD charger still works, just slower.
- Google Pixel: uses PD, and Google lists PPS support for its fastest wired speeds.
- Tablets and laptops: iPads with USB-C, MacBooks and most Windows ultrabooks charge over PD, which is how one charger can cover a whole bag.
If your phone shows "Slow charger" or charges at a crawl on a USB-A brick, PD is almost always the missing piece. See why an iPhone says Slow Charger or why your phone is charging slowly.
06Buying a USB PD charger: a quick checklist
GaN chargers pack the same PD output into a smaller body, which matters if you want one brick for a phone and a laptop. Our GaN charger explainer covers why. If you only charge one phone, a single-port 20W to 30W PD charger is plenty, and it's the cheaper buy.
Pick the wattage for your biggest device. Pair it with a USB-C to USB-C cable rated for the power.
Questions people ask
Is USB-C the same as USB Power Delivery?
No. USB-C is the connector shape. USB Power Delivery is a charging standard that runs over it. Many USB-C chargers support PD, but a cheap USB-C brick might only offer basic 5V power, so check for "PD" on the label.
Is USB PD safe for my phone?
Yes. Nothing above 5V is sent until the phone asks for it and the charger agrees. The phone keeps adjusting the request as it fills and warms up, so a bigger PD charger only delivers what the phone wants.
Does iPhone use USB Power Delivery?
Yes. iPhone 8 and later fast charge with a USB-C PD charger. Apple recommends a 20W or higher adapter. Newer Pro models can use more, but any 20W PD charger gives you proper fast charging.
What's the difference between PD 3.0 and PD 3.1?
PD 3.0 tops out at 100W and introduced PPS. PD 3.1 added Extended Power Range voltages of 28V, 36V and 48V, allowing up to 240W for laptops. For a phone, PD 3.0 with PPS covers everything you need.
Do I need a special cable for USB PD?
Any USB-C to USB-C cable handles up to 60W (3A). Above that you need a 5A e-marked cable, usually sold as 100W or 240W. For phones, a 60W cable is enough, but a 100W one costs little more and covers laptops too.