External Power Transistor Constant Current LED Driver
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Solution Overview
Problem
Existing constant current control circuits with built-in power transistors face challenges of increased chip area and cost, as well as inefficient heat dissipation and current regulation precision.
Innovation Solution
A constant current control circuit design that uses power transistors externally, featuring a current source output module and output circuits with automatic constant current regulating modules, power transistor drive and control modules, and load modules, allowing for dynamic balancing of currents across output circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If power transistors are built-in to the constant current control circuit, then current regulation precision is improved, but chip area increases and cost increases
Solution Approach 1:
The patent extracts the power transistors from the integrated circuit and places them externally. The constant current control circuit now controls external power transistors rather than containing them internally, which reduces chip area while maintaining current regulation precision through the same control mechanism.
Solution Approach 2:
The system is segmented into two parts: the integrated constant current control circuit and the external power transistors. This separation allows the control logic to remain precise while the power handling components are moved outside the chip, resolving the area-precision contradiction.
2Measurement precision
If power transistors are built-in to the constant current control circuit, then current regulation precision is improved, but manufacturing cost increases
Solution Approach 1:
By extracting power transistors from the integrated circuit, the patent reduces manufacturing complexity and cost. The control circuit can be manufactured using standard IC processes while power transistors are handled separately, reducing overall manufacturing cost while preserving regulation precision.
3Measurement precision
If power transistors are built-in to the constant current control circuit, then current regulation capability is improved, but heat dissipation becomes difficult
Solution Approach 1:
The patent moves power transistors external to the integrated circuit, allowing heat to be dissipated outside the chip. This separates the heat-generating power components from the sensitive control circuitry, making heat dissipation easier while maintaining current regulation capability.
4Device complexity
If a simple circuit structure is used to track current changes, then device complexity is reduced, but current regulation speed may be compromised
Solution Approach 1:
The patent implements a feedback mechanism where the circuit tracks current changes in each output and automatically adjusts to maintain balance. This feedback approach enables a relatively simple circuit structure to achieve fast current regulation by continuously monitoring and responding to current variations.
Solution Approach 2:
The circuit dynamically adjusts current distribution based on real-time conditions in each output circuit. This dynamic response allows the simple circuit structure to achieve fast regulation by adapting to changing conditions rather than requiring complex predetermined control logic.
Data Source
AI summary
A constant current control circuit includes a current source output module and at least two output circuits. Each of the output circuits includes an automatic constant current regulating module, a power transistor drive and control module electrically coupled to automatic constant current regulating module, and a load module formed of one or more LED devices and electrically coupled to a power transistor drive and control module. The constant current control circuit in operation tracks changes in current of each output circuit and regulates the currents of all the output circuits accordingly.