Discrete LED Power Circuit with Thermistor Temperature Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing LED power and control circuits using discrete components suffer from large temperature drifts, unstable output electrical currents, and low efficiency due to complex integrated circuits and high working temperatures.
Innovation Solution
A power circuit for LED lighting devices using discrete components, comprising a filtering unit, a rectifying unit, a transformer, and field effect transistors as switches, with a thermistor for temperature compensation, and linear compensation resistors to stabilize output current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If integrated circuits are used for LED power and control circuits, then device functionality is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent divides the power circuit into separate functional modules using discrete components: rectifying unit, filtering unit, transformer, and push-pull oscillating circuit. This segmentation allows each component to perform its specific function independently, avoiding the need for complex integrated circuits while maintaining full control functionality.
Solution Approach 2:
The field effect transistors serve multiple functions: they act as switches in the push-pull oscillating circuit, provide temperature compensation through their characteristics, and enable control functionality. This multi-functionality reduces the need for additional dedicated control components, simplifying the overall circuit structure.
2Device complexity
If discrete components are used with triode master switches, then device complexity is reduced, but temperature drift and output current stability worsen due to high working temperatures
Solution Approach 1:
The patent changes the key parameter from triode to field effect transistor. Field effect transistors have superior temperature characteristics compared to triodes, with lower temperature coefficients and better thermal stability. This parameter change directly addresses the temperature drift issue while maintaining circuit simplicity.
Solution Approach 2:
The patent implements a feedback mechanism where the field effect transistor's gate voltage is controlled by the voltage across the detection resistor, which monitors the output current. This feedback loop automatically adjusts the switch operation to maintain stable output current despite temperature variations, improving reliability without adding circuit complexity.
3Ease of manufacture
If discrete components are used instead of integrated circuits, then manufacturing cost and ease of manufacture improve, but temperature drift and efficiency worsen
Solution Approach 1:
The patent changes the switch type from triode to field effect transistor, which has lower on-resistance and reduced conduction losses. This parameter change improves circuit efficiency by reducing energy dissipation in the switches, while discrete field effect transistors remain cost-effective and easy to manufacture.
Solution Approach 2:
The patent replaces the triode-based control mechanism with a field effect transistor-based electronic control system. Field effect transistors provide more efficient electronic switching with lower power losses compared to triode-based systems, improving overall circuit efficiency while maintaining the discrete component architecture for cost-effectiveness.
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
The solution provides stable and precise output electrical current with reduced temperature drift, enabling efficient LED lighting operation and cost-effective dimming control without complex control circuits.
Implementation Method 1
The grid electrode of the second switch is connected to the source electrode of the first switch through a thermistor
Implementation Method 2
the first switch and the second switch are field effect transistors
Implementation Method 3
a rectifying unit configured to convert the AC to a direct current (DC)
Implementation Method 4
a transformer connected to the rectifying unit
Data Source
AI summary
A power circuit for an LED lighting device using discrete components is provided. The power circuit includes a filtering unit configured to filter an inputted AC and a rectifying unit configured to convert an AC to a DC. The power circuit also includes a transformer connected to the rectifying unit. Further, the power circuit includes a first switch and a second switch that are field effect transistors, wherein a grid electrode of the first switch is connected to a drain electrode of the second switch. Further, a drain electrode of the first switch is connected to the transformer. A source electrode of the first switch is connected to a source electrode of the second switch through a detection resistor. A grid electrode of the second switch is connected to the source electrode of the first switch through a thermistor.