USB-C Power Delivery Explained
USB Power Delivery, or USB PD, is a power-negotiation standard. A compatible power source and device agree on an available operating mode; the connector shape and the adapter's headline wattage alone do not establish the result.
What happens when you connect a phone?
The source advertises supported power capabilities, and the connected device requests an appropriate operating point. The capabilities of the source, device and cable all matter. Think of the adapter’s label as available options rather than a command to push its maximum power into every connected phone.
Read the output label
An adapter might list several voltage and current combinations. Power is voltage multiplied by current, so an illustrative 9 V at 3 A operating point corresponds to 27 W. This arithmetic describes that profile; it does not predict battery charging time.
| Label information | Why to record it |
|---|---|
| Fixed output profiles | Compare with the phone’s documented requirements |
| PPS range, if present | Check a separately supported charging feature |
| Selected port | Different ports may have different capabilities |
| Shared output table | See what changes when another device is attached |
PD and PPS are related, but not interchangeable labels
PPS is a specific feature within the USB PD ecosystem. Do not infer PPS capability from a generic PD claim. Use the PPS guide when the phone manufacturer calls for it.
Build a purchase specification
List the exact handset model, intended adapter port, cable and simultaneous-use scenario. Keep a copy of the manufacturer’s documentation with the order. If a seller cannot identify the adapter’s output profiles, the comparison remains incomplete.
For procurement, ask the seller to confirm the same model and revision across the supplied batch. A product photo that shows a different output label should trigger clarification before approval.
What this guide does not establish
We have not tested a particular charger. The example calculations are illustrations, and USB PD support is not a substitute for checking product provenance or applicable safety documentation. Return to Charging & Power for the complete selection path.
How this guide was prepared
Desk research using the linked primary sources, with AI assistance. Purchasing workflows and numerical examples are editorial illustrations, not product tests or supplier inspections.
Sources and further reading
- USB Charger (USB Power Delivery) — USB-IF. Accessed .
Found an error? See our corrections policy and research methodology.
