**USB-PD Protocol Explanation**
The USB-PD (Power Delivery) communication is a method of transmitting protocol messages by modulating them into a 24 MHz FSK (Frequency Shift Keying) signal, which is then coupled to the VBUS line or extracted from it. This allows the device and charger to communicate with each other during the charging process.
As shown in the diagram, the 24 MHz FSK signal is coupled to the DC voltage on the VBUS using a coupling capacitor. To ensure that this high-frequency signal doesn’t interfere with the power delivery, a low-pass filter composed of an isolation inductor is used to remove the FSK component.
Here’s how the USB-PD protocol works, using a smartphone and a compatible charger as an example:
1. The USB OTG PHY monitors the VBUS voltage. If it detects 5V and the OTG ID pin is pulled down by a 1kΩ resistor (indicating a PD-compatible cable), it confirms that the cable supports USB-PD.
2. The system performs standard BCSV 1.2 charger detection and activates the USB-PD device policy manager. This manager checks for FSK signals on the VBUS and decodes them to retrieve the CapabilitiesSource message, which lists all supported voltages and currents.
3. Based on user settings, the phone selects a voltage/current pair from the CapabilitiesSource and sends a Request message via FSK modulation on the VBUS.
4. The charger decodes the message, sends an Accept response, and adjusts its output accordingly.
5. The phone receives the Accept message and updates its charging parameters through the Charger IC.
6. During charging, the phone can dynamically send new requests to adjust the output voltage and current, enabling faster and more efficient charging.
**What Can a PD Charger Be Used For?**
PD fast charging has become a major trend this year, especially after Google announced that all Android phones must support PD fast charging. This means no more non-PD voltage adjustments via USB ports. China's Ministry of Industry and Information Technology also backs PD fast charging, signaling a move toward a unified charging standard across devices.
One of the most notable devices supporting PD is the Nintendo Switch. While it may not be widely known in mainland China, the Switch made a big splash this year with its Type-C port and PD fast charging capability.
Apple has also played a key role in promoting PD. The new MacBook models use Type-C ports and come with 29W PD chargers. Additionally, the iPhone 8, 8 Plus, and X now support PD fast charging.
Xiaomi is another major supporter of PD. The Xiaomi MIX 2 and the Mi Notebook Pro 15.6 both support PD fast charging. The notebook can charge up to 50% in just 30 minutes, making it one of the fastest options available.
Samsung’s S8 and Note8 also support PD fast charging, along with many Type-C laptops. As PD becomes more widespread, we can expect more devices to adopt it, leading to a more standardized and efficient charging experience.
**Which Chargers Support the PD Protocol?**
**1. Romans MPA830QFD Charger**
This charger is designed for users who want maximum compatibility. It supports USB PD 3.0 and QC 3.0, making it ideal for Apple, Samsung, and Xiaomi devices. With three ports—Type-C, QC, and USB-A—it offers a wide range of outputs, including 20V/1A, 15V/1.4A, 12V/1.5A, 9V/2A, and 5V/3A. Despite being bulky, it features foldable prongs for convenience.
**2. ORICOTSM-1U Charger**
This compact 24W charger supports 5V/3A, 9V/2.5A, and 12V/2A. It works with AC input from 100–240V and features foldable US-style pins. It supports QC fast charging and can even charge the Galaxy Note7 at up to 27W. However, it doesn’t fully support Apple devices.
**3. ACT Anke News APS-PD024W-G**
This 24W PD charger is small, lightweight, and compatible with global sockets. It supports 12V/2A, 9V/2.5A, and 5V/3A, and has passed multiple certifications like CCC, CE, and UL. Its sleek design makes it easy to carry.
**4. Green Union CD127**
This charger is designed with a simple, Apple-like look and supports 5V/3A, 12V/2A, 14.5V/2A, and 20V/1.45A. It’s perfect for MacBook and iPad Pro users who want to avoid buying expensive original chargers.
**5. Apple Original Charger A1540**
This 14.5V/2A charger was released with the 12-inch MacBook in 2015. It supports global voltage inputs and has a replaceable plug, making it versatile for international use. Priced at around 388 yuan, it’s a premium option for Apple users.
**6. Xiaomi Air Charger ADC6501TM**
Designed for the Xiaomi Air 13.3 notebook, this 65W charger supports USB PD 3.0 and offers a wide range of outputs, including 5V/2A, 9V/2A, 12V/2A, 15V/3A, and 20V/3.25A. It’s ideal for users who need high power for notebooks and smartphones.
**7. Huawei MateBook Charger HW-59C200CHPQ1**
This lightweight charger supports both Type-C and MicroUSB ports. It weighs only 110g and provides 5V/2A, 9V/2A, or 12V/1A outputs. It’s great for charging the MateBook and Android devices alike, making it a smart choice for multi-device users.
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