With the release of WPC Qi 2.0, Qi 2.0 certification has caught the attention of many wireless charging solution providers and related industries. The launch of Qi 2.0 has injected fresh blood and vitality into wireless charging, bringing countless opportunities and challenges. The convenience and safety of wireless charging are being recognized by users, and the market demand for wireless charging is growing stronger.

01. Solution Principles and Development Status

What is Wireless Charging?

Wireless charging, simply put, is a technology that allows devices to charge without using conductive wires. It uses principles like electromagnetic induction, electromagnetic resonance, or other technologies that use magnetic fields as a power transmission bridge. The necessary devices are installed at both the transmitting and receiving ends to send and receive the generated alternating current signals, thus completing the charging process.

Mobile phone wireless charging uses the electromagnetic induction method: the primary coil generates alternating current at a certain frequency, which induces a current in the secondary coil via electromagnetic induction, thereby transferring energy from the transmitter to the receiver.

图1 无线充原理图 摘自百度百科

What is Qi 2.0?

Any digital device with the Qi logo can be charged using a Qi wireless charger. Qi 2.0 is an upgraded version of Qi, a newly enhanced wireless charging standard developed by the Wireless Power Consortium (WPC). The charging power of Qi 2.0 has been increased from 7.5W in Qi 1.3 to 15W. Additionally, the existing BPP and EPP protocols have been optimized, forming a new MPP (Magnetic Power Protocol) for better compatibility and higher charging efficiency.

With the release of Qi 2.0, the charging power has been significantly increased, and the maximum input voltage at the transmitting end can reach 19V to reduce current and lower coil losses, thus improving efficiency. This imposes a requirement on the transmitter's ICs to have a voltage rating of ≥19V.

02. High-Performance PMIC Solution

The diagram below shows a transmission-side solution based on the MPP protocol by Silicon Content Technology. The adapter provides 9V voltage, which is stepped up to 9.5-19V by the SCT12A2 to power the full bridge. After security authentication through the authentication IC, and handshaking between the MCU and receiving end, the MCU controls the full bridge to generate alternating current in the coil, which causes changes in the magnetic field to realize electromagnetic conversion and complete wireless charging.

MPP Transmission-side Solution Block Diagram

Solution Analysis:

• SCT12A2: A boost IC, which in the Qi 2.0 standard, requires a maximum charging power of 15W. To improve efficiency, the voltage needs to be increased to reduce current. In the Qi 2.0 standard, the maximum voltage can reach 19V. Therefore, a boost chip is required after the adapter to step up the output voltage and supply power to the full bridge.
• SCT63240A: The full bridge generates alternating current in the coil under the control of the MCU, enabling electromagnetic conversion; an LDO powers the MCU; a Buck regulator supplies power to low-power wireless charging applications, such as for watches.
• Authentication IC: This is a security chip that provides anti-counterfeiting certification, communication protection, and data security, ensuring safe high-power charging. Qi 2.0 certification requires authentication as part of the standard.
• MCU: The MCU communicates with the receiving end and adjusts the output voltage of the BOOST chip, controlling the full bridge's output power through duty cycle modulation to match the receiving end's charging requirements.

03. Silicon Content Technology Product Introduction

PMIC Solution—SCT63240A

The SCT63240A integrates a full bridge, LDO, and BUCK in one chip. The full bridge has a voltage rating of 20V and a power output of 20W, integrating a 3.3V/200mA LDO and a 5V/1A BUCK. This eliminates the need for an additional LDO to power the MCU, significantly simplifying the TX schematic and reducing both costs and component count.

• VIN Wide Input Voltage Range: 4.2V-20V
• PVIN Wide Input Voltage Range: 1V-20V
• Up to 20W Output Power
• 14.5mΩ Rdson MOSFET Integrated Full Bridge Power Stage
• Efficient 5V-1A Buck DC/DC Converter Integrated
• Optimized for EMI Reduction
• Built-in 3.3V-200mA LDO
• Integrated Lossless Input Current Sensor with ±2% FOD and Current Demodulation Accuracy
• 3.3V and 5V PWM Logic Compatible Signals
• Undervoltage Lockout
• Overcurrent Protection
• Overtemperature Protection
• QFN-19L 3mm x 4mm Package

BOOST Solution—SCT12A2

The SCT12A2 is a boost IC capable of outputting up to 21V, with a switch current of 15A and an output power of over 30W, fully meeting the Qi 2.0 requirements. It drives a P-MOSFET for load switching, solving the problem of BOOST ICs not fully shutting down.

• Wide Input Voltage Range: 2.7V-20V
• Wide Output Voltage Range: 4.5V-21V
• Integrated 13mΩ High-Side FET and 11mΩ Low-Side FET
• Efficiency Up to 96% for Vin=7.2V, Vout=15V, Iout=2A
• Peak Switch Current Up to 15A with Programmable Peak Current Limit
• P-Channel MOSFET Load Disconnect Control
• Typical Shutdown Current: 1uA
• Programmable Switching Frequency: 200kHz-1.0MHz
• Frequency Modulation Mode
• Programmable Soft-Start
• Output Overvoltage Protection
• Overtemperature Protection at 150°C
• DFN-20L 3.5mmx4.5mm Package

BOOST Upgrade Solution—SCT12A5

The SCT12A5 provides significant improvements in efficiency and size:

1. Efficiency: Under conditions of 9V input and 17V output at 21W, the efficiency reaches 97%.
2. Size: A smaller QFN3x4 package for space optimization.

• Wide Input Voltage Range: 2.7V-20V
• Wide Output Voltage Range: 4.5V-21V
• Integrated 10mΩ High-Side FET and 6.5mΩ Low-Side FET
• Efficiency Up to 97% for Vin=9V, Vout=18V, Iout=1.3A
• Peak Switch Current Up to 21.5A with Programmable Peak Current Limit
• Typical Shutdown Current: 1uA
• Static Current: 300uA
• Fixed 400kHz Switching Frequency
• Multiple Operating Modes: PFM, USM, and FPWM
• Programmable Soft-Start
• Output Overvoltage Protection
• Overtemperature Protection at 150°C
• QFN-13 3mm x 4mm Package

Currently, both SCT12A2 and SCT63240A have been in stable mass production for over 3 years. Samples for testing are available upon request, and you can contact sales or email to sales@silicontent.com for sample requests or orders.