Adaptive LED Dimming Circuit for Voltage Mismatch Compensation
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Solution Overview
Problem
Inconsistent forward voltages across LED strings due to manufacturing differences lead to inefficient LED dimming and driving systems, requiring a smart dimming solution that provides proper driving voltage and improves efficiency.
Innovation Solution
A dimming module and system that includes calculating circuits to adjust current duty cycle and magnitude reference signals based on feedback voltages, with a feedback amplifying circuit and pulse generating circuit to ensure consistent current flow across LED strings, using a feedback voltage detection mechanism to differentiate and adjust signals for strings with minimum and maximum feedback voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LEDs are arranged in multiple paralleled strings with a common LED driver, then the system can meet different brightness requirements, but the forward voltage differences due to manufacturing variations cause inconsistent current flow and reduced efficiency
Solution Approach 1:
The patent divides the LED driving system into multiple independent dimming modules, each dedicated to a specific LED string. Each module independently regulates current for its associated string, allowing customized control that compensates for manufacturing variations in forward voltage, thereby maintaining high efficiency across all strings while meeting different brightness requirements.
Solution Approach 2:
The patent implements dynamic current regulation where each dimming module continuously adjusts its current output based on real-time feedback from its LED string. This dynamic adaptation allows the system to compensate for forward voltage differences and maintain optimal efficiency under varying operating conditions.
2Device complexity
If a common current reference signal is used for all LED strings, then the control is simplified, but the forward voltage differences result in inconsistent current flow and improper dimming
Solution Approach 1:
The patent segments the current control into multiple independent dimming modules, each with its own current reference signal generation and regulation circuitry. This segmentation allows each module to independently optimize current delivery for its specific LED string, compensating for manufacturing variations while maintaining overall system manageability through modular architecture.
3Device complexity
If the current magnitude reference signal is not adjusted for minimum feedback voltage strings, then the control logic is simpler, but the LED efficiency and driver efficiency are reduced
Solution Approach 1:
The patent applies local quality by having each dimming module independently adjust its current magnitude reference signal based on the specific feedback voltage characteristics of its associated LED string. This localized adaptation ensures that each string operates at optimal efficiency points, with modules for strings having minimum feedback voltage applying appropriate compensation to maintain high LED efficiency.
Data Source
AI summary
A dimming module having: a calculating circuit, configured to receive a preset current duty cycle reference signal, a preset current magnitude reference signal and a feedback voltage of an associated light-emitting device string, and to provide a current duty cycle reference signal and a current magnitude reference signal; and a current regulating circuit, configured to receive the feedback voltage of the associated light-emitting device string, the current duty cycle reference signal and the current magnitude reference signal, and to control a duty cycle and a magnitude of the current flowing through the associated light-emitting device string; wherein the current magnitude reference signal provided to the light-emitting device string with the minimum feedback voltage is lower than the preset current magnitude reference signal, while the current magnitude reference signal provided to each other light-emitting device string is higher than the preset current magnitude reference signal.