LED Driving Circuit Common Current Sensing Resistor
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Solution Overview
Problem
Conventional LED driving circuits using AC power supplies face challenges in satisfying power factor and total harmonic distortion standards, and impose space limitations due to the need for voltage detection and logical circuits to manage current paths in LED groups.
Innovation Solution
A light emitting diode (LED) driving circuit with a switch unit, current measuring unit, and current control unit that forms multiple current paths between a common node and mid nodes, allowing for selection based on control signals and differential amplification to manage current flow efficiently, eliminating the need for separate logical circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional LED driving circuits use voltage detection circuits and logical circuits to manage current paths, then the power factor and efficiency are improved, but the device complexity and space requirements increase
Solution Approach 1:
The patent combines the voltage detection function and logical circuit functions into a single integrated circuit that performs both functions simultaneously. The circuit uses operational amplifiers and transistors to detect voltage levels and control current paths without requiring separate logical circuits, thereby reducing device complexity while maintaining power factor improvement capabilities
Solution Approach 2:
The driving circuit is designed to perform multiple functions using a unified structure. The same circuit components that detect voltage levels also control the current path selection, eliminating the need for dedicated logical circuits. This multi-functional approach reduces the overall circuit complexity while achieving both power factor correction and efficient current management
2Measurement precision
If separate sensing resistors are used for detecting phase voltage in each LED group, then the current control precision is improved, but the device complexity and space requirements increase
Solution Approach 1:
The patent employs a single sensing resistor that serves multiple detection purposes. The same sensing resistor is used to detect currents across different LED groups by switching the measurement path through transistors controlled by the operational amplifiers. This eliminates the need for separate sensing resistors for each LED group, reducing the circuit board area while maintaining detection precision through the multi-functional sensing approach
3Adaptability or versatility
If voltage detection circuits and logical circuits are added to manage current paths, then the adaptability to AC power supply levels is improved, but the device complexity increases
Solution Approach 1:
The patent integrates voltage detection and logical control functions into a unified circuit architecture. Operational amplifiers detect voltage levels and simultaneously control transistor switching to manage current paths. This merging of detection and control functions into a single integrated system improves adaptability to different AC power supply levels while avoiding the need for separate logical circuits, thereby reducing overall circuit complexity
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 solution enables efficient current management and power factor improvement without the need for additional logical circuits, enhancing integration and reducing space requirements in LED driving systems.
Implementation Method 1
a current measuring unit configured to detect a current flow through the common node
Implementation Method 2
a current control unit configured to generate the control signal based on the detected current flow
Data Source
AI summary
A light emitting diode (LED) driving circuit that sequentially drive a plurality of series-coupled LED groups comprising at least one LED is provided. The LED driving circuit includes a plurality of mid nodes coupled to terminals of the plurality of the LED groups, a common node with a reference voltage, a switch unit configured to form a plurality of current movement paths between the common node and the plurality of the mid nodes and configured to select a current movement path based on a control signal, a current measuring unit configured to detect a current flow through the common node, and a current control unit configured to generate the control signal based on the detected current flow.