LED Current Controller Power Supply Using Output Capacitor
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Solution Overview
Problem
LED lighting systems face issues with constant current controller chips malfunctioning due to input voltage drops below threshold levels, particularly when using TRIAC dimmers, leading to increased costs from external capacitors used as power supplies.
Innovation Solution
A power supply controller and driver system that generates signals to control a transistor based on cathode voltage thresholds, ensuring stable power to the current controller chip through an output capacitor, eliminating the need for external capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external capacitor is used as power supply to the constant current controller chip when input voltage falls below threshold, then the controller chip can operate normally, but the bill of materials cost increases
Solution Approach 1:
The patent merges the power supply function into the existing output capacitor that is already part of the LED driving circuit. Instead of adding a separate external capacitor specifically for powering the controller chip, the invention utilizes the existing output capacitor to serve dual purposes: driving the LED and providing power to the controller chip during low input voltage conditions. This eliminates the need for additional external components and reduces bill of materials cost while maintaining reliable controller operation.
2Adaptability or versatility
If TRIAC dimmer is used to provide dimming function in LED lighting system, then consumers can have unique visual experience, but the rectified voltage is pulled down below threshold causing controller chip to malfunction
Solution Approach 1:
The patent implements a preliminary action by detecting the input voltage level before it drops below the threshold. When the input voltage is detected to be below the threshold (such as during TRIAC dimmer off periods), the system proactively activates the power supply controller to charge the output capacitor, ensuring sufficient voltage is available for the controller chip before it is needed. This prevents controller malfunction by preparing the power supply in advance during dimming operations.
3Reliability
If the transistor is kept turned on to charge the output capacitor, then power supply stability is improved, but energy loss increases
Solution Approach 1:
The patent implements periodic action by controlling the transistor to switch between on and off states rather than remaining continuously on. The power supply controller periodically activates the transistor to charge the output capacitor when input voltage is below threshold, then turns it off when the capacitor is sufficiently charged. This pulsed charging approach maintains power supply stability while significantly reducing energy loss compared to continuous conduction, as the transistor only conducts when necessary to replenish the capacitor.
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
Stabilizes power supply to current controllers, preventing malfunctions and reducing material costs by eliminating the need for external capacitors.
Implementation Method 1
an output capacitor (e.g., Cout) connected to the cathode of the diode
Implementation Method 2
a transistor (e.g., M1), the transistor including a source terminal coupled to the driver and a first resistor, the transistor further including a drain terminal coupled to the one or more light emitting diodes
Data Source
AI summary
System and method for controlling one or more light emitting diodes. For example, the system includes: a power supply controller configured to receive a cathode voltage from a cathode of a diode, the diode including an anode configured to receive a rectified voltage generated by a rectifying bridge, the power supply controller being further configured to generate a first signal based at least in part on the cathode voltage; and a driver configured to receive the first signal and generate a second signal based at least in part on the first signal, the driver being further configured to output the second signal to a gate terminal of a transistor, the transistor including a source terminal coupled to the driver and a first resistor, the transistor further including a drain terminal coupled to the one or more light emitting diodes and an output capacitor connected to the cathode of the diode.