Demystifying PD Charging Principles and Proprietary Protocols in One Article
“Why does the same charger charge my phone quickly but my tablet slowly?” “Why can a laptop charger fast-charge a phone, but not vice versa?” The core of these questions lies in charging protocols — the “communication language” between devices and chargers. Among them, the PD protocol is the universal mainstream, while proprietary protocols are manufacturers’ “exclusive recipes.” This article will help you fully understand them.
Ⅰ. The Underlying Logic of Fast Charging: The Core Formula for Power
Charging speed is determined by power, and power (P) = voltage (V) × current (I). Traditional charging uses a fixed 5V voltage with a low power limit. Fast charging breaks this limit through two paths: one is the high-voltage scheme, increasing voltage while maintaining current; the other is the high-current scheme, boosting current while stabilizing voltage. These different technical paths have spawned two major camps: PD protocols and proprietary protocols.
Ⅱ. PD Charging: The “Official Language” of Universal Fast Charging
USB Power Delivery (PD) is an open standard developed by the USB-IF association, known as the “universal language” in the fast charging field. The latest PD 3.1 version supports a maximum power of 240W, covering almost all devices from phones to workstations.
Its core is an intelligent negotiation mechanism, completing “communication” through the CC (Configuration Channel) pin of the USB-C interface:
Initial connection: After the charger is plugged in, it first outputs a default 5V voltage, and simultaneously detects the device type and cable capability through the CC line.
Capability broadcasting: The charger sends a “Source_Capabilities” message, listing supported voltage/current combinations (e.g., 5V/3A, 9V/3A, 20V/5A).
Request matching: The device selects the optimal configuration based on its own battery status and sends a “Request” message in response.
Power supply confirmation: The charger adjusts to the target voltage, replies with “Accept,” and then stably supplies power at the negotiated power.
The advantage of the PD protocol is its universality. It is supported by all Apple devices (after iPhone 8), Android flagships, and mainstream laptops, and can also achieve bidirectional charging (e.g., a laptop powering a phone).
III. Proprietary Protocols: The “Exclusive Dialect” for Extreme Speed
Proprietary protocols are customized fast charging technologies by mobile phone manufacturers, featuring “low voltage and high current” as their core characteristic. Representatives include OPPO’s VOOC and Huawei’s SCP. They shift the voltage boosting process to the charger side, directly outputting low-voltage and high-current (e.g., 5V/6A) suitable for the battery, significantly reducing heat generation during phone charging.
The advantages of such protocols are prominent: fast and stable charging. OPPO’s 150W SuperVOOC can fully charge a 5400mAh battery in 17 minutes, and its safety has been verified through in-depth customization. However, the drawback is equally obvious — extremely poor compatibility. Fast charging can only be triggered with original chargers and data cables; using third-party accessories will downgrade to normal charging speed.
Ⅳ. PD vs. Proprietary Protocols: A Future of Coexistence and Integration
PD protocols and proprietary protocols are not opposing. Versions of Qualcomm’s QC 4+ and above have been fully compatible with PD, and new models from manufacturers such as Huawei and OPPO also support basic PD fast charging, but full-speed charging still requires proprietary protocols to trigger.
For users, the selection logic is clear: those with multiple devices should prioritize GaN chargers supporting PD 3.1 to achieve “one charger for all”; brand users pursuing extreme fast charging experiences need to match original proprietary protocol accessories. With the advancement of the “integrated fast charging” national standard, seamless adaptation of different protocols is expected in the future, completely solving the problem of fast charging chaos.
Do you need me to create a simplified English comparison table of PD and mainstream proprietary protocols, including key parameters like maximum power and compatibility?
