Constant Current LED Driver Circuit with Multiple Outputs
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Solution Overview
Problem
Existing LED driver technologies for multiple outputs are either complex and costly due to independent DC/DC converters or custom-built voltage-controlled circuits with high design costs, and lack effective current sharing capabilities.
Innovation Solution
A simple and cost-effective constant current control circuit for LED drivers with multiple outputs, featuring a single-output constant current power supply, current sharing circuit, and current sharing control circuit, where the LED load and current sharing circuit form a series loop, using a current sharing resistor and linear regulator to ensure equivalent current output across all circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple independent DC/DC constant current circuits are used, then current sharing capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple constant current circuits into a single constant current power supply with multiple output circuits. Instead of using independent DC/DC converters for each output, the invention combines them into one unified power supply unit that distributes current to multiple LED strings through shared inductors and control circuits, thereby reducing overall system complexity while maintaining current sharing capability
Solution Approach 2:
The single constant current power supply is designed to serve multiple functions by providing current to multiple output circuits simultaneously. The power supply unit performs the constant current regulation function for all LED strings through a unified control mechanism, making the system more versatile and cost-effective while ensuring proper current distribution across all outputs
2Reliability
If custom-built voltage regulated circuits are used, then current sharing is achieved, but design cost increases
Solution Approach 1:
The patent employs parameter changes through adjustable output voltage in the voltage regulated circuit. By dynamically adjusting the output voltage parameter of the first stage circuit based on feedback from the LED strings, the system achieves proper current sharing without requiring custom-built complex circuits. This parameter adjustment mechanism simplifies the design while maintaining current sharing capability
Solution Approach 2:
The invention implements feedback control through voltage feedback from the LED string outputs back to the voltage regulated circuit. This feedback mechanism enables the system to automatically adjust the output voltage to maintain proper current sharing, eliminating the need for complex custom-built circuits and reducing design costs while ensuring reliable current distribution
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 a low-cost, efficient current sharing mechanism that automatically maintains current balance across multiple outputs, reducing design complexity and operational costs while ensuring reliable current sharing without relying on a single frontend constant current circuit.
Implementation Method 1
a voltage regulated circuit with adjustable output voltage connected with multiple linear regulation constant current circuit
Implementation Method 2
The output voltage of the first stage is always higher than a maximum output voltage of the multiple linear regulated constant current circuits, resulting in minimum power loss
Data Source
AI summary
A constant current control circuit with multiple outputs for a LED driver, the circuit including a single-output constant current power supply, and multiple output circuits, each output circuit comprising a current sharing circuit, a current sharing control circuit and a LED load. The LED load and the current sharing circuit are in series and form a series loop with a first terminal and a second terminal of the series loop connected to a first output terminal and a second output terminal of the constant current power supply.