What is QC (Quick Charge)

This page provides a detailed explanation of QC (Quick Charge) in 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 battery charging protocol independently developed by Qualcomm, a US company engaged in mobile communication technology and semiconductor design and development. It is primarily used to manage the power supplied via USB by negotiating voltage between the power source and the device.

Quick Charge is a proprietary technology that enables charging battery-powered compact electronic devices such as smartphones at ratings exceeding the standard USB specification of 5.0V/2.0A. In the field of such rapid charging methods for AC/DC Power Adapters — Desktop & Wall-Mount, many companies offer proprietary competing technologies, including MediaTek's Pump Express and Oppo's VOOC.

This protocol is adopted by various manufacturers’ fast charging systems, including mobile devices equipped with Qualcomm's SoCs, and can be observed in items such as wall-mount AC/DC Power Adapters — Desktop & Wall-Mount and car chargers. Note that both the device and the charger must support the QC charging method in order for QC charging to work.

History of QC (Quick Charge)

2012, Official Announcement of USB PD

In 2012, the USB Implementers Forum (USB-IF), a non-profit organization founded to promote Universal Serial Bus, including USB, Wireless USB, and USB On-The-Go, announced the finalization of the USB Power Delivery (USB PD) specification. This groundbreaking new technology enabled devices to draw up to 100W of power via supported USB ports. It was first adopted in a prototype of Xiaomi’s Mi Mix 3, achieving full charge from 1% to 100% in 17 minutes.

The Emergence of Quick Charge 1.0 & 2.0

Quick Charge 1.0, developed in 2013, supported only the Snapdragon 600 chipset from Qualcomm’s mobile SoC series. The voltage remained USB standard (5V), but the current was set to 2A—about one-third higher than BC 1.2 current.

Quick Charge 2.0 was the first to gain significant popularity as a new standard for rapid charging and supported many versions of the above-mentioned Snapdragon. The main difference from Quick Charge 1.0 was that while the current was still limited to a maximum of 2A, the voltage could be increased to up to 12V. This approach was developed to address the fact that most cables connecting USB and MicroUSB terminals at the time did not support currents above 2.4A, which could result in overheating accidents (because heat loss is proportional to the square of the current and resistance). Qualcomm chose a method that increased only the voltage. As a result, the maximum power output increased from 10W (5.0V/2.0A) in the initial QC version to 18W (12.0V/1.67A) in QC 2.0.

An optional feature called Dual Charge (originally called Parallel Charging) was also introduced, which used two PMICs to split the power flow and reduce the device temperature.

The Emergence of Quick Charge 3.0

In 2015, Qualcomm developed Quick Charge 3.0. It essentially utilized the same technology as Quick Charge 2.0 while enabling 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 the optional Dual Charge+. INOV is an algorithm that determines the optimal power transfer while maximizing efficiency. The Battery Saver aims to maintain at least 80% of the original charging capacity after 500 charge cycles. According to Qualcomm’s announcement, compared to Quick Charge 2.0, Quick Charge 3.0 achieved up to 4–6°C lower temperatures, 16% faster charging, and 38% improved efficiency. When using Dual Charge+, further improvements were observed: up to 7–8°C lower temperatures, 27% faster charging, and 45% greater efficiency compared to Dual Charge in QC 2.0.

In an experiment using a 2750mAh battery, a traditional AC/DC Power Adapter — Desktop & Wall-Mount (5.0V/1.0A) only charged the battery up to 12% in 30 minutes. In contrast, using Quick Charge 3.0 allowed the device to charge from 0% to 80% in 35 minutes. Quick Charge 3.0 supports USB Type-A, USB Type-C, Micro USB, and even proprietary connectors.

The Emergence of Quick Charge 4.0 and 4.0+

In December 2016, Qualcomm announced Quick Charge 4.0 along with Snapdragon 835.

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 specifications. If either the AC/DC Power Adapter — Desktop & Wall-Mount or the device does not support the spec, it can fall back to USB PD. Additional features include protections against overheating, over-voltage, over-current, and cable quality detection. Qualcomm announced that Quick Charge 4 using Dual Charge++ is up to 5°C cooler, 20% faster, and 30% more efficient compared to Quick Charge 3.0 using Dual Charge+.

Quick Charge 4+ was then announced on June 1, 2017. Qualcomm introduced advanced safety functions such as Intelligent Thermal Balancing, which autonomously uses temperature-lower current paths to eliminate hot spots and optimize power delivery, providing protection from overheating, short circuits, and damage to USB Type-C connectors.

The Latest Quick Charge 5

After covering Quick Charge chronologically, we arrive at the announcement of Quick Charge 5 on July 27, 2020.

Although widespread adoption is still pending, Qualcomm announced that Quick Charge 5 can deliver up to 100W of power on smartphones equipped with a 4500mAh battery, enabling a 50% charge in just 5 minutes. This standard is compatible with USB PD and, during dual-cell charging, communicates with AC/DC Power Adapters — Desktop & Wall-Mount to double the voltage and current. For instance, a single battery requests 8.8V of power. Dual cells together request a PPS (Programmable Power Supply) charger to output 17.6V, which is then split between two individual batteries, outputting a total of 5.6A to achieve 100W.

Unifive's QC Chargers

We are continuously expanding our lineup of compact USB PD products with QC functionality. Unlike consumer power supplies distributed on the market, our products are designed based on standards for professional use. If you have any questions regarding samples or products, please feel free to contact our sales team.