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How does mobile phone fast charging work?
APR. 28, 2020 | Newsletter Issue 36

Can you remember life before your first mobile phone? Smart phones have become essential to daily life and phone chargers have evolved over the years as much as the phones they charge. Today’s mobile phone charging technology allows charging at extremely high currents and is able to reach a full charge in less than an hour. Richtek has been involved in mobile phone charging systems from the beginning, and we thought it would be interesting to explain the evolution of charging systems by means of a tutorial video.

In this video, we will explain different battery types and their charging requirements from the early mobile phones with low power charging to the latest generation phones with high power charging systems. We will also cover special charging systems like Qualcomm’s Quick-Charge QC2.0/3.0 and explain the details of the new USB-C Power Delivery charging systems, covering Direct Charge and Direct Charge-Divide/2 systems that can deliver charging powers up to 45W without overheating.

At the end of the video, we will tell you about next generation smartphone charging technology like how Direct Charge-Divide/4 solves the problem of the high current through the charging cable while still achieving up to 60W charging power.

Interested? Please have a look at the video: The Technology behind Mobile Phone Fast Charging.

Watch the video for the evolution of fast charging

We have also bookmarked specific sections, like Battery types and charging curves, Higher Voltage Charging, Type-C Power Delivery communication, 25W USB-PD travel Adapter, Direct Charge, Direct Charge Divide/2 and Direct Charge- Divide/4.

Products mentioned in this video

❶ The design example of USB Type-C PD travel adapter

The design example of USB Type-C PD travel adapter
RT7755 New
PWM Controller for Programmable Power Converter

Designed to work with the PD controllers such as RT7206. Optimised for adaptive output power with 10V to 60V wide VDD range. High efficiency at light load and comprehensive protection features for USB PD adaptor applications.

RT7220B New
Synchronous Rectifier Controller

Suitable for low-side SR control of flyback in CCM, DCM and quasi-resonant mode. Designed to support a wide VOUT range of 3.3V to 13V for USB PD adapter applications.

RT7206A New
Highly Integrated USB PD Controller

The USB PD controller with an integration of the internal feedback compensation, blocking N-MOSFETs and the current sense. Specifically designed for off-line AC-DC converters to possess the high-power density for USB adapter source side.

❷ The design example of USB Type-C PD travel adapter

The design example of Direct Charge
RT1716
USB-PD 3.0 Power Delivery Controller

Compliant with the latest USB Type-C and PD standards. Integrating the physical layer of the USB BMC power deliver protocol to allow up to 100W of power and role swap. Suitable for sink side USB applications.

RT1731
Cable ID for USB Type-C Cables

Electronically-marked ID cable controller for both passive and active full-featured USB type-C cables complied with USB type-C and PD3.0. Ideal for high current & active USB cables.

RT9748
6A Smart Load Switch Battery Charger

Integrating an internal load switch with charge pump control and 4-path constant current/constant voltage regulation, a 5-way hardware protection, and a 10-channel 12-bit analog-to-digital converter.

❸ The design example of USB Type-C PD travel adapter

The design example of Direct Charge Divide/2
RT9759 New
Smart Cap Divider Charger

Integrating a dual phase charge pump core for Direct Charge-Divide by 2. Featuring 4-error charge pump switch protections, multiple system protections & system alarms, 12-bit ADC etc. Delivering up to 8A of charging current.

❹ Products for battery charger applications

RT9467
5A Single-cell Switching Battery Charger

with power path management and USB OTG-Boost for high current applications.

RT9471
3A Single-cell Switching Battery Charger

for medium current applications.

RT9465
3A Single-cell Slave Switching Battery Charger

for high current applications.

❺ Others

RTQ7880-QT
USB Type-C PD and PWM Buck-Boost Controller with AnyPowerTM and PD Safe® Features

AEC-Q100 Grade 2 qualified, designed for automotive USB type-C PD chargers.

RT7207K
Highly Integration USB PD Controller with Synchronous Rectification

Ideal for USB PD Type-C or other proprietary protocols chargers/adapters for smart phones, NBs, tablets, etc.

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fast charging USB PD USB Power Delivery Battery charger Direct Charge
Coronavirus news

Richtek can help

The whole world is fighting the COVID-19 pandemic. At Richtek, our top priority is our employees’ health and safety and we have taken several preventive measures to ensure this.

Richtek is a true believer that technology can help in these difficult times. We have given highest priority to the production and shipment of ICs to customers who urgently needed Richtek parts for building sub-systems of medical ventilator machines that are currently needed worldwide.

We are monitoring the situation at our production partners on a daily basis to ensure the impact of COVID-19 on Richtek supply chain is as low as possible. As a brand built on innovation and professionalism, we will continue our regular communications with you.

Stay safe, stay healthy.

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