Fairchild Semiconductor AN-9729 LED Application Design Guide Using Half-Bridge LLC Resonant Converter for 100W Street Li

About this manual

This document is an application note describing the design of an LED driving system using a half-bridge LLC resonant converter. It addresses the limitations of conventional PWM DC-DC converters for high-power LED lighting, such as low efficiency at light loads, and proposes the LLC topology to improve efficiency and reduce system volume. The note focuses on outdoor or street lighting applications requiring 100W output.

What's inside

• Introduction
• Consideration of LED Drive
• Consideration of LLC Resonant Converter
• LLC Resonant Converter and Fundamental Approximation
• Square-Wave Generator
• Resonant Rectifier Network
• Design Procedure
• Design Example

Frequently asked questions

What specific lighting applications is this half-bridge LLC resonant converter designed for?

This application note describes the LED driving system using a half-bridge LLC resonant converter for high power LED lighting applications, such as outdoor or street lighting.

How does controlling the current through an LED affect its light output?

The amount of current through an LED determines the light it emits, and brightness can be controlled directly by changing the LED current.

What is the typical range for the longevity of LEDs compared to fluorescent tubes?

LED lighting has greater longevity than fluorescent tubes, lasting 5 to 20 times longer.