LED Driving Apparatus Voltage Ripple Controller
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Solution Overview
Problem
LED driving apparatuses using PWM dimming signals face issues with flickering and shaking due to fine current or voltage changes, particularly in low grayscale conditions, which affect user perception.
Innovation Solution
An LED driving apparatus with a voltage ripple controller and a switching unit that adjusts the voltage supplied to the LED driving circuit based on the duty ratio of the PWM dimming signal, using a combination of constant voltage elements and resistances to control the voltage ripple, thereby preventing flickering and shaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If PWM dimming method is used to adjust LED brightness, then output brightness can be controlled, but fine current difference occurs due to low frequency ripple of input voltage causing flickering in low grayscale conditions
Solution Approach 1:
A voltage ripple controller is introduced as an intermediary component between the power supply unit and LED driving circuit. This controller actively suppresses voltage ripple through its internal circuitry, preventing the ripple from reaching the LED driving circuit and causing flickering, while still allowing PWM dimming to function for brightness control.
Solution Approach 2:
The voltage ripple controller changes the voltage parameter by actively regulating and stabilizing the voltage level, removing ripple components. This parameter transformation converts the unstable rippled voltage into a stable DC voltage, eliminating the cause of flickering in low grayscale conditions while preserving PWM dimming capability.
2Illumination intensity
If additional dimming FET is used in LED driving apparatus, then output brightness can be adjusted, but device complexity increases
Solution Approach 1:
The voltage ripple controller is designed to perform multiple functions: it suppresses voltage ripple to prevent flickering and simultaneously enables PWM dimming for brightness control. By integrating these functions into a single component, the need for additional dimming FETs is eliminated, reducing device complexity while maintaining brightness adjustment capability.
3Stability of the object's composition
If voltage ripple controller is turned on continuously, then voltage stability is improved, but power consumption increases
Solution Approach 1:
The voltage ripple controller operates dynamically by switching between on and off states based on real-time detection of voltage ripple conditions. When ripple is detected, the controller activates to stabilize voltage; when ripple is absent, it deactivates to conserve power. This dynamic operation maintains voltage stability when needed while minimizing power consumption during normal operation.
Solution Approach 2:
The system employs feedback control where the voltage ripple controller continuously monitors the voltage output from the power supply unit. Based on this feedback, it determines when ripple is present and activates only during those periods. This feedback mechanism ensures voltage stability is maintained when necessary while avoiding unnecessary power consumption during stable operation.
Data Source
AI summary
Disclosed is an LED driving apparatus. The LED driving apparatus comprises an LED driving circuit, a power supply unit for supplying a driving voltage to the LED driving circuit, a voltage ripple controller located between the LED driving circuit and the power supply unit, and a switching unit for controlling a voltage supplied to the LED driving circuit by turning on or off the voltage ripple controller according to a duty ratio of a pulse width modulation (PWM) dimming signal.