Apple fast charging, specifically for iPhones, works by delivering a higher amount of power to the device for a faster charge, particularly in the initial stages.
The Basics of iPhone Fast Charging
Traditionally, iPhones charged at lower wattages (e.g., 5W). Fast charging significantly increases this power delivery, allowing your iPhone battery to reach up to 50% capacity in around 30 minutes. This is achieved through the USB Power Delivery (PD) standard, which requires both a compatible iPhone model and a USB-C power adapter with sufficient wattage (typically 20W or higher) connected via a USB-C to Lightning cable.
Power Delivery (PD) and PDOs
The USB PD standard allows devices and chargers to communicate and negotiate the optimal power levels for charging. Power adapters supporting PD offer different "Power Data Objects" (PDOs), which are essentially pre-defined voltage and current combinations they can provide.
According to the reference, iPhone PD fast charging usually involves both PDO1 and PDO2 from the power adapter.
The Charging Process Explained
- Initial Power Boost: At the very beginning of the charging cycle, the iPhone communicates with the PD charger. Because PDO2 has a higher voltage than PDO1, PDO2 is used at the start to deliver an initial boost of power for a short period of time. This higher power allows the battery to gain a significant charge quickly.
- Later Stages: After this initial boost phase, the charging process typically shifts to a lower power level to protect the battery health as it gets closer to being full. While the reference specifically highlights the initial use of PDO2, the device and charger continue to manage power delivery throughout the charge cycle, likely utilizing other PDOs or adjusted power levels.
Why You Need the Right Accessories
To benefit from Apple fast charging, you need:
- Compatible iPhone: iPhone 8 or later models support fast charging.
- Compatible Power Adapter: A USB-C power adapter of 20W or higher that supports USB Power Delivery. Examples include Apple's 20W USB-C power adapter or compatible third-party options.
- Compatible Cable: A USB-C to Lightning cable.
Using a standard USB-A to Lightning cable or a lower-wattage adapter will result in standard charging speeds, not fast charging.
PDOs in Simple Terms
Think of PDOs as different "gears" the charger can use to deliver power.
| PDO | Voltage | Typical Usage Phase | Purpose |
|---|---|---|---|
| PDO1 | Lower Voltage | Later/Standard Charging | Efficient charging after initial boost |
| PDO2 | Higher Voltage | Start (Short Period) | Initial power boost for fast charging |
By leveraging the higher voltage PDO (PDO2) at the start, Apple's fast charging can quickly juice up your iPhone when the battery is most depleted, providing significant power in a short time.
