Auxiliary Circuit Pre-Charges LED Driver Capacitor
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Solution Overview
Problem
Current dimmable LED driving circuits with large electrolytic capacitors and small duty ratios of dimming signals experience prolonged start-up times for LED loads.
Innovation Solution
Incorporating an auxiliary circuit and a current control loop to charge the electrolytic capacitor when its voltage is below a preset value, using a voltage source for pre-charging and an error amplifier for continuous charging until the start-up voltage is reached, thereby reducing the start-up time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrolytic capacitor is large in capacitance to ensure stable operation, then the stability is improved, but the start-up time becomes too long
Solution Approach 1:
The patent applies preliminary action by introducing an auxiliary circuit that pre-charges the electrolytic capacitor before the main driving circuit activates. This pre-charging phase establishes an initial voltage on the capacitor, so when the main circuit starts, the capacitor is already partially charged, significantly reducing the overall start-up time while maintaining the necessary capacitance value for stable operation.
2Illumination intensity
If the duty ratio of the dimming signal is small to achieve dimming effect, then the brightness regulation is improved, but the start-up time becomes too long
Solution Approach 1:
The auxiliary circuit performs preliminary charging of the electrolytic capacitor independent of the dimming signal duty ratio. This ensures that regardless of how small the duty ratio is set for dimming purposes, the capacitor receives sufficient pre-charging current to establish the necessary voltage foundation, thereby decoupling the start-up time from the dimming duty ratio setting.
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
This approach significantly accelerates the start-up speed of the dimmable LED driving circuit by ensuring the electrolytic capacitor reaches the necessary voltage more quickly, enhancing the circuit's efficiency and stability.
Implementation Method 1
charging the electrolytic capacitor by controlling a current loop of the electrolytic capacitor by an auxiliary circuit using a voltage source
Implementation Method 2
continuously charging, when the voltage across the electrolytic capacitor rises to the preset value, the electrolytic capacitor by controlling the current loop of the electrolytic capacitor by a current control loop circuit using an error amplifier
Data Source
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AI summary
An integrated circuit, a dimmable LED driving circuit and a driving method thereof are provided. The dimmable LED driving circuit includes an electrolytic capacitor. In the embodiment of the present disclosure, when the voltage across the electrolytic capacitor is less than a preset value, the electrolytic capacitor is additionally charged by an auxiliary circuit to reduce the time required for the voltage across the electrolytic capacitor rising to a start-up voltage of an LED load, thereby increasing the start-up speed of the dimmable LED driving circuit.