Overview
Wireless charging originates from wireless power transfer technology. Low-power wireless charging commonly uses electromagnetic induction, such as the Qi method for charging phones, while higher-power wireless charging often uses resonant coupling. Because energy is transferred between the charger and the powered device via a magnetic field, no wired electrical connection is required and no conductive contacts need to be exposed.
Mainstream wireless charging standards include Qi, PMA, A4WP, and iNPOFi. Qi was introduced by the Wireless Power Consortium (WPC) as a standardized wireless charging specification, offering convenience and interoperability. Devices marked with the Qi label can be charged by Qi chargers. Qi aims to provide a common charging method for phones, cameras, laptops, and other products, enabling wider adoption of wireless charging.
Market implementations of wireless charging mainly use three approaches: electromagnetic induction, radio wave transmission, and resonance. Qi adopts electromagnetic induction, which is the most widely used approach. Companies in China are active in the wireless charging industry. Qi applications in the Chinese market are primarily phones and portable digital devices.
Key Features
- Complies with WPC Qi 1.1 standard, with foreign object detection (FOD)
- High integration with built-in efficient synchronous rectification and battery charge management
- Integrated MCU to ensure system flexibility
- Built-in 12-bit high-precision ADC
- Maximum charging current: 400 mA @ 5 V
- Single-pin selectable battery voltage: 4.2 V or 4.35 V
- Reverse current protection; standby current < 0.1 uA
- Input voltage tolerance up to 20 V
- Built-in over-current, over-voltage, and over-temperature protection
