LED Driver Circuit Dynamic Voltage Regulation
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Solution Overview
Problem
LED driver circuits face challenges in accurately regulating voltage and maintaining current accuracy at low dimming duty cycles, particularly due to the 'turn on' time limitations and insufficient feedback during the transition state, which affects their ability to support low dimming duty cycles effectively.
Innovation Solution
The method involves varying the regulated voltage value based on the dimming duty cycle, using a function that decreases monotonically with increasing duty cycle, and employing a DC-DC converter with dimming control circuitry and regulated voltage determination circuitry to generate control signals, ensuring adequate voltage for accurate current tracking across LED channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed regulated voltage value is used for all dimming duty cycles, then the circuit is simple to operate, but current accuracy deteriorates at low dimming duty cycles
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed regulated voltage value to a variable regulated voltage value that dynamically adjusts based on the dimming duty cycle. The circuit determines a regulated voltage value based on the detected dimming duty cycle, allowing the voltage to change adaptively. This resolves the contradiction by maintaining operational simplicity while achieving high current accuracy across all dimming levels through dynamic voltage adjustment.
Solution Approach 2:
The patent changes the voltage parameter from a fixed value to a variable value that depends on the dimming duty cycle parameter. By making the regulated voltage a function of the dimming duty cycle, the circuit can maintain accurate current tracking across different operating conditions. This parameter change enables the system to optimize performance for both high and low dimming duty cycles.
2Use of energy by moving object
If the regulated voltage is kept at minimum to reduce power consumption, then energy efficiency improves, but the ability to support low dimming duty cycles deteriorates
Solution Approach 1:
The circuit dynamically adjusts the regulated voltage based on the dimming duty cycle, allowing it to operate at minimum voltage for high duty cycles (optimizing power consumption) while automatically increasing the voltage when low duty cycles are detected (maintaining adaptability). This dynamic behavior resolves the contradiction between energy efficiency and adaptability.
Solution Approach 2:
The patent changes the voltage parameter adaptively based on operating conditions. When the dimming duty cycle is low, the circuit increases the regulated voltage above minimum to maintain adequate power delivery and current accuracy. When the duty cycle is high, it operates at minimum voltage to optimize energy efficiency. This conditional parameter change resolves the contradiction.
3Measurement precision
If feedback blanking is applied during turn on time, then measurement precision during transition is improved, but the time available for voltage regulation deteriorates
Solution Approach 1:
The circuit performs preliminary action by determining the regulated voltage value based on the dimming duty cycle before the actual voltage regulation occurs. By pre-calculating or pre-determining the appropriate voltage level based on the detected duty cycle, the circuit can quickly adjust the voltage without waiting for extended feedback periods, thus reducing the time loss while maintaining measurement precision during transition.
Data Source
AI summary
An LED driver circuit selects a regulated voltage value for use in driving one or more LEDs based on dimming duty cycle. In some embodiments, the regulated voltage value may be selected in accordance with a function that decreases monotonically with increasing dimming duty cycle. In this manner, LED current accuracy can be achieved at lower dimming duty cycles, while still achieving enhanced operational efficiency at higher dimming duty cycles.