Synchronous LED Driver Startup for Deep Dimming Circuits
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Solution Overview
Problem
The challenge of synchronizing the startup of LED power supplies with different dimming depths leads to response delays and unpleasant user experiences due to varying charging times of electrolytic capacitors.
Innovation Solution
A synchronous start-up circuit and constant current deep dimmable power supply are introduced, utilizing enabling and starting switch circuits to control the discharge of LED luminaires simultaneously by using synchronized start signals and power-off signals based on reaching the starting voltage of each LED luminaire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the charging current is reduced to achieve deep dimming depth, then the brightness control range is improved, but the charging time increases causing startup desynchronization
Solution Approach 1:
The patent applies preliminary action by pre-charging the electrolytic capacitor through the constant current source before the LED luminaire is fully powered on. The enabling switch circuit is activated in advance to charge the capacitor, and once the voltage reaches the starting voltage threshold, the starting switch circuit is triggered to simultaneously power on all LED luminaires. This ensures that even with deep dimming depths requiring long charging times, all luminaires start up synchronously.
2Reliability
If the capacitance of electrolytic capacitors is increased to reduce current ripple, then the output stability is improved, but the charging time increases causing startup desynchronization
Solution Approach 1:
The patent uses preliminary action by having the constant current source pre-charge the electrolytic capacitor before the LED luminaire operates. The enabling switch circuit is activated in advance to charge the capacitor to the required voltage level. Once charging is complete and the voltage reaches the starting voltage threshold, the starting switch circuit is triggered to simultaneously power on all LED luminaires. This allows large capacitance values that ensure output stability without causing startup desynchronization.
3Adaptability or versatility
If multiple LED power supplies with different dimming depths are used, then the adaptability is improved, but the startup synchronization is lost
Solution Approach 1:
The patent applies preliminary action by pre-charging all electrolytic capacitors through their respective constant current sources before simultaneous startup. The controller activates the enabling switch circuits in advance for all LED luminaires, allowing each capacitor to charge to its required voltage level independently. Once all capacitors reach the starting voltage threshold, the controller triggers the starting switch circuits simultaneously for all luminaires, ensuring synchronous startup regardless of different dimming depths.
Solution Approach 2:
The patent uses feedback by monitoring the voltage across each electrolytic capacitor through the enabling switch circuit. When the voltage reaches the starting voltage threshold, the enabling switch circuit generates a signal to trigger the starting switch circuit. This feedback mechanism ensures that all LED luminaires are ready for simultaneous startup, eliminating startup desynchronization even when multiple luminaires have different dimming depths.
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
Ensures simultaneous and timely startup of LED luminaires, eliminating response delays and enhancing user experience by coordinating the power supply to all LED luminaires.
Implementation Method 1
it is necessary to increase the capacitance of electrolytic capacitors in the output circuit to reduce current ripple
Implementation Method 2
the voltage across its terminals is proportional to the charging current, so the required charging time is longer
Implementation Method 3
a constant current source for a LED luminaire
Data Source
AI summary
A synchronous start-up circuit with a constant current deep dimmable power supply; when the output voltage of the current source does not reach the start voltage of an LED luminaire, the circuit is disconnected; when the output voltage reaches the start voltage of the LED luminaire, an enabling switch circuit turns on and outputs a power-off signal, which is used for controlling the current source to wait for the output voltage of other constant current sources to reach the start voltage of the corresponding LED luminaire. When the output voltage of the constant current source reaches the starting voltage of the corresponding LED luminaire, each starting switch circuit receives a synchronized starting signal, each starting switch circuit is turned on, and each current source discharges to supply power for the LED luminaire.