Sunday, February 9, 2025

Qi Wireless Charging LED Lantern Reference Design

Looking to add wireless charging to your designs? Explore a solution that combines Qi 1.1 compatibility, battery charging, and LED driving in one package. Read more!

Qi® Wireless Charging LED Lantern Reference Design
Qi Wireless Charging LED Lantern Reference Design

The Qi wireless charging LED lantern reference design from Microchip is a versatile and cost-effective solution for design engineers looking to integrate wireless charging into their applications. The design features a Qi 1.1 standard receiver, supporting a maximum power of 5W, and utilizes an 8-bit microcontroller for seamless communication and charging.

This lantern is compatible with any wireless charging transmitter and includes a fully functional Lithium-Ion charging controller, along with the high efficiency of a switching power supply. Using this reference design, engineers can quickly add wireless charging functionality to various applications.

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The reference design is portable and flexible, making it suitable for various use cases. It features a Qi 1.1 compatible wireless receiver, enabling the possibility of encapsulating the final product for dust- and waterproof applications.

Key features of the lantern include receiver implementation using a general-purpose 8-bit microcontroller, enabling easy integration into different systems and applications. The lantern is also compatible with the Qi 1.1 (5W) standard, making it suitable for any Qi 1.1 compatible wireless charging transmitter. Additionally, the lantern features accurate power measurement, which aids in the Foreign Object Detection (FOD) function, ensuring safe and efficient charging.

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The design showcases a Qi 1.1 receiver implementation and a bidirectional switching power supply for battery charging and LED driving. This design demonstrates how to use a Qi 1.1 wireless receiver to charge a Lithium-Ion battery, then boost the battery voltage to power a string of LEDs. The system is powered by a PIC16F18325 microcontroller along with several analog components.

The design has several notable features. The input voltage from the wireless receiver coil ranges from +4.5V to +28V. It uses a +5V supply for low voltage power, regulated by an MCP1804 LDO. The design implements the Qi 1.1 5W wireless charger communication protocol in the microcontroller’s firmware. It is intended to work with a 2000 mAh Li-Ion battery, charging at 1A with a voltage of 4.2V. The system drives a 3-LED string with a maximum current of 200 mA at 9V.

The reference design uses a synchronous buck converter topology, ensuring high efficiency. It also incorporates a bidirectional buck or boost converter, driven by a PFM signal. This converter provides both charging and discharging modes: buck mode to charge the battery and boost mode to power the LED string from the battery. Additionally, the design includes a full charging algorithm for Lithium-Ion batteries, implemented in firmware. For the LEDs, four dimming levels are available: 25%, 50%, 75%, and 100%.

Microchip has tested this reference design. It comes with a bill of materials (BOM), schematics, assembly drawing, printed circuit board (PCB) layout, and more. The company’s website has additional data about the reference design. To read more about this reference design, click here.

Nidhi Agarwal
Nidhi Agarwal
Nidhi Agarwal is a Senior Technology Journalist at EFY with a deep interest in embedded systems, development boards and IoT cloud solutions.

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