LED Driver Feedback Control for Stable Low-Voltage Start-Up
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Solution Overview
Problem
Existing LED drivers face inefficiencies and safety issues during start-up due to unpredictable LED intensity variations and voltage fluctuations, leading to excessive power dissipation and potential instability in light output.
Innovation Solution
An LED driver with a controller that measures voltage drops and generates a feedback signal to regulate the power supply output voltage between minimum and maximum levels, ensuring a safe and stable start-up by maintaining the initial voltage at a minimum level until the system is fully operational.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power supply provides excess voltage to ensure sufficient voltage margin for current regulator operation, then the reliability of LED operation is improved, but the power dissipation in the current regulator increases
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the forward voltage of the LEDs and dynamically adjusts the power supply output voltage accordingly. This closed-loop control ensures that the power supply provides exactly the necessary voltage margin for current regulator operation without excessive voltage, thereby reducing power dissipation while maintaining reliable LED operation.
Solution Approach 2:
The system transitions from a static voltage provision approach to a dynamic adjustment mechanism. The controller adaptively modifies the power supply output voltage based on real-time LED forward voltage measurements, allowing the system to optimize the voltage margin dynamically rather than providing a fixed excess voltage, thus reducing energy loss while ensuring operational reliability.
2Reliability
If the controller starts up and provides feedback signal at first feedback signal value representing minimum power supply output voltage, then the safety during start-up is improved, but the light output intensity is reduced
Solution Approach 1:
The controller performs preliminary action by initializing the feedback signal at the first feedback signal value (representing minimum power supply output voltage) before full operation begins. This preliminary state ensures safe start-up conditions where voltage and current are limited, preventing component damage during initialization, and then progressively transitions to normal operating levels.
Solution Approach 2:
The system implements a staged startup sequence where the feedback signal transitions from the first feedback signal value (minimum voltage for safety) to the second feedback signal value (maximum voltage for full intensity) over time. This periodic transition allows the system to safely initialize at low intensity and then gradually increase to full light output as components stabilize.
Data Source
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AI summary
An LED driver comprises a current source and a power supply configured to provide a power supply output voltage to the current source. The LED driver further comprises a controller configured to measure a voltage drop over the current source and to generate a feedback signal in response to the measured voltage drop. The power supply comprises a power supply regulator configured to regulate the power supply output voltage of the power supply between a minimum power supply output voltage and a maximum power supply output voltage, the power supply regulator comprising a power supply regulator input. The feedback signal is provided to the power supply regulator input, in a range from a first feedback signal value representing a minimum power supply output voltage to a second feedback signal value representing a maximum power supply output voltage. At a start-up of the LED driver, the controller provides the feedback signal at the first feedback signal value, and the power supply regulator, in response to receiving the first feedback signal value, controls the power supply to provide the minimum power supply output voltage.