What is QC (Quick Charge)?

On this page, we provide a detailed explanation of QC (Quick Charge) in AC/DC Power Adapter. It is a convenient charging method that enables rapid charging of small electronic devices such as smartphones.

What is QC (Quick Charge)?

Quick Charge is a battery charging protocol independently developed by Qualcomm, a U.S. company engaged in mobile communication technology and semiconductor design and development. It is primarily used to manage power supplied via USB by communicating with the power source and negotiating voltage.

Quick Charge is a proprietary technology that enables charging of small battery-powered electronic devices such as mobile phones at ratings exceeding the basic USB standard of 5.0V/2.0A. In the field of fast-charging methods for this type of AC/DC Power Adapter, many companies have their own competing technologies, such as MediaTek's Pump Express and Oppo's VOOC system.

This protocol is adopted not only in mobile devices equipped with Qualcomm SoCs but also in fast-charging systems from various manufacturers. It can be found in wall-mounted AC/DC Power Adapters and car chargers. Note that QC charging cannot be performed unless both the device and the charger support the QC charging standard.

History of QC (Quick Charge)

2012: Official Announcement of USB PD

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

The Emergence of Quick Charge 1.0 and 2.0

Developed in 2013, Quick Charge 1.0 supported only Qualcomm's Snapdragon 600 mobile SoC chipset. While the voltage remained at the USB standard (5V), the current was set to 2A, approximately one-third higher than BC 1.2.

The first version to gain significant popularity as a new fast-charging standard was Quick Charge 2.0, which supported many versions of the Snapdragon series. The main difference from Quick Charge 1.0 was that the current was limited to a maximum of 2A while the voltage could increase up to 12V. This approach was taken because many USB and Micro USB cables at the time did not support currents above 2.4A, posing a serious risk of overheating (since heat loss is proportional to the square of the current times resistance). Qualcomm therefore chose to increase only the voltage. As a result, maximum power increased from 10W (5.0V/2.0A) in the original QC version to 18W (12.0V/1.67A) in QC 2.0.

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

The Emergence of Quick Charge 3.0

In 2015, Qualcomm developed Quick Charge 3.0. It utilizes fundamentally the same technology as Quick Charge 2.0 but enables 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 that determines optimal power transfer while maximizing efficiency. Battery Saver aims to maintain at least 80% of the battery's original capacity after 500 charge cycles. According to Qualcomm, Quick Charge 3.0 achieves up to 4-6C lower temperatures, 16% faster charging, and 38% greater efficiency compared to Quick Charge 2.0. When using Dual Charge+, it achieves up to 7-8C lower temperatures, 27% faster charging, and 45% greater efficiency compared to Quick Charge 2.0 with Dual Charge.

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

The Emergence of Quick Charge 4.0 and 4.0+

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

Quick Charge 4 features HVDCP++, optional Dual Charge++, INOV 3.0, and Battery Saver Technologies 2. It supports both USB Type-C and USB PD specifications and can fall back to USB PD if either the AC/DC Power Adapter or the device does not support QC. It also adds protection measures against overheating, overvoltage, and overcurrent, as well as cable quality detection. Qualcomm announced that Quick Charge 4 with Dual Charge++ achieves up to 5C lower temperatures, 20% faster charging, and 30% greater efficiency compared to Quick Charge 3.0 with Dual Charge+.

Quick Charge 4+ was later announced on June 1, 2017. It introduced advanced safety features such as Intelligent Thermal Balancing, which optimizes power delivery by autonomously using the coolest current path and eliminating hot spots, providing protection against overheating, short circuits, and USB Type-C connector damage.

The Latest Quick Charge 5

Following the chronological introduction of Quick Charge versions, Quick Charge 5 was announced on July 27, 2020.

Although widespread market adoption may still take time, Qualcomm announced that Quick Charge 5 enables up to 100W of power for smartphones equipped with a 4500mAh battery, allowing 50% charge in just 5 minutes. This standard is interoperable with USB PD. The technology communicates with the AC/DC Power Adapter when charging dual cells, doubling voltage and current values. For example, a single battery cell may require 8.8V. A dual-cell configuration can request 17.6V output from a PPS (Programmable Power Supply) charger, which is then split in half to charge two separate batteries, delivering a total current of 5.6A to achieve 100W.

Unifive QC Chargers

We are continuously expanding our lineup of compact QC-enabled USB PD products. Unlike consumer power supplies commonly available on the market, our products are designed based on standards intended for industrial use. If you have any questions regarding samples or Products, please feel free to contact our sales department.