Buck Converter with Auxiliary Switches for LED Current Regulation
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Solution Overview
Problem
Existing buck converters for LEDs are often too expensive for mass production, necessitating a cost-effective power supply solution that can efficiently regulate current to LEDs.
Innovation Solution
A two-point controller buck converter is designed using bipolar transistors to set switch-on and switch-off times based on the base-emitter forward voltage, allowing for simple and cost-effective implementation with auxiliary switches, enabling continuous operation from a low-voltage DC source and defining maximum and minimum current values for LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If integrated circuits are used for LED power supply, then current regulation performance is improved, but implementation cost increases
Solution Approach 1:
The integrated circuit is divided into discrete components (buck converter circuit, auxiliary switches, bipolar transistors) that can be implemented separately. This segmentation allows for cost-effective implementation using individual components rather than expensive integrated circuits, while maintaining the functional performance of current regulation.
Solution Approach 2:
The patent replaces expensive integrated circuits with cheaper discrete components including bipolar transistors and auxiliary switches. These components are more economical for mass production applications, achieving cost reduction while maintaining adequate current regulation performance for LED driving.
2Ease of manufacture
If bipolar transistors are used for switches, then implementation cost is reduced, but device complexity increases
Solution Approach 1:
The auxiliary switches serve multiple functions: they detect current levels, control the timing of the buck main switch, and regulate LED current. This multi-functionality reduces the need for additional dedicated components, simplifying the overall circuit despite using bipolar transistors.
Solution Approach 2:
The bipolar transistors and auxiliary switches automatically regulate the LED current based on their inherent electrical characteristics (base-emitter forward voltage). The circuit self-adjusts the switch-on and switch-off times without requiring external control logic, reducing complexity despite the use of discrete transistor components.
3Measurement precision
If two-point controller is used, then current regulation precision is improved, but control complexity increases
Solution Approach 1:
The auxiliary switches provide feedback about the LED current status to the control circuit. This feedback mechanism enables precise two-point control by continuously monitoring the current and adjusting the buck main switch timing accordingly, achieving accurate current regulation through a relatively simple control structure.
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 configuration results in a highly economical power supply circuit for LEDs, reducing implementation costs and space requirements compared to integrated circuits, while ensuring non-zero minimum current and adjustable current values, facilitating operation from both low-voltage and mains voltage sources.
Implementation Method 1
the buck converter is to be constructed in such a way that it is possible to determine the switch-on and switch-off times of the buck main switch only by the base-emitter forward voltage of a small-signal bipolar transistor
Implementation Method 2
a buck choke and a buck main switch having a control electrode, a working electrode and a reference electrode
Data Source
AI summary
The present invention relates to a buck converter for providing a current for at least one LED (D2, D3, D4, D5) having an input with a first (E1) and a second input terminal (E2) for connecting a DC voltage source (V1); an output having a first (A1) and a second output terminal (A2) for connecting the at least one LED (D2, D3, D4, D5); and a buck diode (D1), a buck throttle (L1), and a buck main switch (Q2), which has a control electrode, a work electrode, and a reference electrode; wherein said buck diode (D1) and said buck main switch (Q2) are serially coupled between said first (E1) and said second input terminal (E2), wherein said buck throttle (L1) is coupled between the connection point of the buck diode (E1) and the buck main switch (Q2) and the first output terminal (A1), and wherein said buck converter further comprises: a first auxiliary switch (Q4), to which a first voltage (UR3) is supplied, which is correlated with the current (ILED) provided at the at least one LED (D2, D3, D4, D5); and a second auxiliary switch (Q5), to which a second voltage (UR2) is supplied, which is correlated with the current provided to the at least one LED (D2, D3, D4, D5), wherein said first auxiliary switch (Q4) and said second auxiliary switch (Q5) are coupled to said buck main switch (Q2) such that the shutoff moment of said buck main switch (Q2) is established by said first voltage and the startup moment of said buck main switch (Q2) is established by said second voltage. In addition, the invention relates to a corresponding method for providing a current for at least one LED (D2, D3, D4, D5) using a buck converter.