Constant-Current LED Driver with Adaptive Reference Voltage Control
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Solution Overview
Problem
Conventional constant-current driving circuits face inefficiencies and heat generation due to fixed output signals that do not adapt to variations in LED strings, leading to suboptimal voltage drops and increased energy loss.
Innovation Solution
A dynamic constant-current driving circuit that adjusts its reference voltage based on comparing signals generated from the LED string's voltage and operation voltage, optimizing the output signal to match the LED string's requirements, thereby minimizing heat generation and efficiency loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed reference voltage is used in the constant-current driving circuit, then the circuit structure is simple, but the output signal cannot be optimized for different LED strings causing efficiency loss and heat generation
Solution Approach 1:
The patent applies dynamics by making the reference voltage adjustable through a switchable resistor network. The equivalent resistance of the resistor network can be dynamically changed by switching between different resistor connections, allowing the reference voltage to be optimized for different LED string configurations while maintaining a relatively simple circuit structure.
Solution Approach 2:
The patent changes the resistance parameter of the resistor network to optimize the output signal. By switching between different equivalent resistances (R1, R2, or their series/parallel combinations), the reference voltage can be adjusted to match different LED string requirements, improving adaptability without significantly increasing circuit complexity.
2Reliability
If a high output voltage is applied to ensure current source operation, then the current source operates normally, but excess voltage causes efficiency loss and heat generation
Solution Approach 1:
The patent uses feedback control where the adjustable reference voltage is compared with the actual voltage across the LED string. The switching controller adjusts the resistor network configuration based on this comparison to optimize the output voltage, ensuring the current source operates reliably while minimizing excess voltage and energy loss.
Solution Approach 2:
The patent dynamically adjusts the output voltage by switching between different resistor network configurations. This allows the system to match the output voltage closely to the LED string requirements, ensuring current source operation stability while reducing the voltage margin that causes efficiency loss and heat generation.
3Adaptability or versatility
If fixed resistors are used for voltage division, then the circuit is simple to manufacture, but the output signal cannot be optimized for variations in LED forward bias voltage
Solution Approach 1:
The patent replaces fixed resistors with a switchable resistor network that can dynamically change its equivalent resistance. This allows the voltage division ratio to be optimized for different LED forward bias voltages while maintaining manufacturing simplicity, as the same physical resistors are used in different configurations rather than requiring multiple sets of resistors.
Solution Approach 2:
The patent makes the resistor network multi-functional by enabling it to serve different purposes through switching. The same resistor components can be connected in different configurations (series, parallel, or individual) to provide different reference voltages, making the circuit adaptable to various LED strings without requiring additional components.
Data Source
AI summary
A constant-current driving circuit includes a first current source, a reference voltage generating circuit and an output signal generating circuit. A terminal of the first current source is coupled to a terminal of a first LED string, wherein the terminal of the first current source has a first voltage. The reference voltage generating circuit is used for generating a reference voltage and comparing the first voltage with a first predetermined voltage to generate a first comparing signal to thereby adjust the reference voltage. The output signal generating circuit is used for outputting an output signal to another terminal of the first LED string and receiving the input signal, wherein the output signal generating circuit decides whether or not to output the input signal serving as the output signal according to the comparison result of the reference voltage with the second voltage.