What is QC (Quick Charge)?

This page provides a detailed explanation of QC (Quick Charge) for AC/DC Power Adapters — Desktop & Wall-Mount. It is a convenient charging method that enables fast charging for small electronic devices such as smartphones.

What is QC (Quick Charge)?

Quick Charge is a proprietary battery charging protocol developed by Qualcomm, a U.S.-based company specializing in mobile communication technologies and semiconductor design. It is used primarily to manage power delivery via USB by negotiating voltage between the power supply and communication lines.

Quick Charge is a proprietary technology that enables small battery-powered electronic devices such as mobile phones to be charged at rates exceeding the standard 5.0V/2.0A defined by USB specifications. In the field of AC adapter fast charging methods like this, many companies offer competing proprietary technologies, such as MediaTek’s Pump Express system and Oppo’s Vooc technology.

This protocol has been adopted not only in Qualcomm SoC-equipped mobile devices but also in rapid charging systems from various manufacturers, and can be seen in wall-mounted AC adapters and car chargers. It should be noted that both the device and the charger must support QC technology to utilize Quick Charge.

History of QC (Quick Charge)

Official USB PD Announcement in 2012

In 2012, USB Implementers Forum (USB-IF), a nonprofit organization founded to promote USB, wireless USB, and USB On-The-Go technologies, officially announced the finalization of the USB Power Delivery (USB PD) standard. This enabled devices to draw up to 100W of power via supported USB ports. This revolutionary technology was first implemented in a prototype of Xiaomi’s Mi Mix 3, achieving rapid charging from 1% to 100% in just 17 minutes.

Introduction of Quick Charge 1.0 & 2.0

Quick Charge 1.0, developed in 2013, was compatible only with Qualcomm’s Snapdragon 600 mobile SoC series. It maintained the USB standard voltage (5V) but increased the current to 2A, about one-third higher than BC 1.2.

The first version to gain widespread popularity as a new standard for fast charging was Quick Charge 2.0, which supported many versions of the above Snapdragon chipset. The main difference from Quick Charge 1.0 was limiting current to 2A while increasing voltage up to 12V. This was done to prevent overheating accidents, which could occur due to USB and Micro USB cables not supporting currents above 2.4A — since heat loss is proportional to the square of the current and resistance. Qualcomm addressed this by increasing only the voltage instead of the current. As a result, whereas the maximum power output of the original QC version was 10W (5.0V/2.0A), QC 2.0 delivered up to 18W (12.0V/1.67A).

An optional feature called Dual Charge (originally referred to as Parallel Charging) was also introduced, splitting power into two streams using two PMICs to reduce device temperature.

Introduction of Quick Charge 3.0

In 2015, Qualcomm developed Quick Charge 3.0. It fundamentally builds upon the same technology as Quick Charge 2.0 but allows even faster charging when used with compatible devices.

Quick Charge 3.0 introduced INOV (Intelligent Negotiation for Optimal Voltage), Battery Saver, HVDCP+ (High Voltage Dedicated Charging Port), and optional Dual Charge+. INOV is an algorithm for determining optimal power transfer while maximizing efficiency. Battery Saver aims to retain at least 80% of the original charge capacity after 500 charge cycles. According to Qualcomm, Quick Charge 3.0 achieves up to 4–6°C lower temperatures, 16% faster charging, and 38% better efficiency compared to Quick Charge 2.0. When using Dual Charge+ with QC 3.0, the improvements increase to 7–8°C lower temperatures, 27% faster charging, and 45% greater efficiency.

In a test with a 2750mAh battery, using a traditional AC adapter (5.0V/1.0A) charged the device only 12% in 30 minutes, whereas Quick Charge 3.0 charged it from 0% to 80% in just 35 minutes. Quick Charge 3.0 supports USB Type-A, USB Type-C, Micro USB, and proprietary connectors.

Introduction of Quick Charge 4.0 and 4.0+

In December 2016, Qualcomm announced Quick Charge 4.0 alongside the Snapdragon 835 chipset.

Quick Charge 4 includes HVDCP++, optional Dual Charge++, INOV 3.0, and Battery Saver Technologies 2. It supports both USB Type-C and USB PD standards. If either the AC adapter or the device is not compatible, the system supports fallback to USB PD. Additional features include protection against overheating, overvoltage, and overcurrent, as well as cable quality detection. According to Qualcomm, Quick Charge 4 using Dual Charge++ is up to 5°C cooler, 20% faster, and 30% more efficient than Quick Charge 3.0 with Dual Charge+.

Later, Quick Charge 4+ was announced on June 1, 2017. Qualcomm introduced advanced safety features such as Intelligent Thermal Balancing, which autonomously chooses the cooler current path and eliminates hotspots, thus optimizing power delivery and preventing overheating, short circuits, and USB Type-C connector damage.

Introduction of the Latest Quick Charge 5

Continuing the chronological presentation of Quick Charge technologies, Quick Charge 5 was announced on July 27, 2020.

Though its market adoption is still in early stages, according to Qualcomm, Quick Charge 5 enables up to 100W of power in smartphones equipped with a 4500mAh battery, achieving 50% charging in just 5 minutes. The standard is fully USB PD-compatible and includes the ability to double voltage and current during dual-cell charging through communication with the AC adapter. For example, each battery cell may require 8.8V. Then, the dual-cell system outputs 17.6V from a PPS (Programmable Power Supply) charger, splits it into two separate batteries, and delivers a combined current of 5.6A to achieve 100W.

Unifive’s QC Chargers

We are continuously adding compact USB PD products with QC functionality to our lineup. Unlike consumer-grade power supplies commonly available on the market, our products are designed based on standards intended for industrial use. For samples or any questions about products, please feel free to contact our sales team.