LED Control Circuit Consolidating PFC and Driver Stages
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Solution Overview
Problem
Existing LED control circuits are complex due to the requirement of three separate switching control stages for power factor correction, switched-mode power supply, and LED driver, limiting simplicity and efficiency in LED control applications.
Innovation Solution
Integration of power factor correction, switching power supply, and LED driver functions into a single clocked stage using a flyback converter with rectified mains half-waves as input, enabling continuous dimming through current feedback and microprocessor-controlled reference voltage adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three separate switching control stages (PFC, SWT, LED driver) are used, then power factor correction and LED driving functions are achieved, but circuit complexity increases
Solution Approach 1:
The patent combines three separate switching control stages (PFC, SWT, and LED driver) into a single integrated circuit that performs all functions simultaneously. The controller unit integrates the control logic for power factor correction, switched-mode power supply, and LED constant current driving in one unified stage, eliminating the need for three separate stages and reducing overall circuit complexity.
Solution Approach 2:
The single switching control stage is designed to perform multiple functions: power factor correction, voltage conversion via switched-mode power supply, and constant current regulation for LEDs. This multi-functional approach allows one circuit to replace three separate circuits, achieving the same overall effect with reduced complexity.
2Illumination intensity
If conventional dimming with LED driver stage modulation is used, then LED brightness can be adjusted, but the number of dimming stages is limited by switching frequency ratio
Solution Approach 1:
The patent adjusts the reference voltage for current feedback before the LED driver stage operates, allowing continuous dimming control without being constrained by switching frequency ratios. By modifying the reference voltage that sets the target current level, the system can achieve any brightness level continuously rather than in discrete steps.
Solution Approach 2:
The patent changes the reference voltage parameter to control LED brightness continuously. Instead of modulating the LED driver stage with limited frequency ratios, the system varies the reference voltage for current feedback, which directly controls the output current level and enables continuous dimming across the full brightness range.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Simplifies LED control by consolidating three stages into one, allowing for continuous dimming and adaptive brightness control based on sensors and external signals, improving efficiency and functionality in LED lighting systems.
Implementation Method 1
a rectifier bridge for generating rectified mains half-waves
Implementation Method 2
a flyback converter whose input is supplied with the rectified mains half-waves
Implementation Method 3
current feedback of the output current of the flyback converter via a shunt resistor
Data Source
AI summary
The invention relates to an electronic circuit for controlling LEDs, comprising: a rectifier bridge for generating rectified mains half-waves, a flyback converter whose input is supplied with the rectified mains half-waves, and a current return of the output current of the flyback converter via a shunt resistor.