Single Inductor LED Driver Circuit for Component Reduction
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Solution Overview
Problem
Conventional LED driving circuits are complex and costly due to the need for multiple chips and components, including additional power supply chips and inductors, which complicates constant current control and dimming functionality.
Innovation Solution
An LED driving circuit using a single inductor that integrates a power stage circuit, constant current controller, and constant voltage generating circuit to provide both constant current control and a reserve supply voltage for a dimming controller without an additional power supply chip, simplifying the peripheral components and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional LED driving circuit uses separate power supply chip and voltage converter, then constant current control and dimming functionality are achieved, but device complexity and product cost increase
Solution Approach 1:
The patent combines the power supply chip and voltage converter into a single integrated circuit. The power stage circuit includes a power transistor, rectifying transistor, and inductor that work together with the constant current controller to provide both constant current control for LED strings and generate supply voltage for the dimming controller through a shared power supply network, eliminating the need for separate power supply chips and reducing circuit complexity.
Solution Approach 2:
The power stage circuit serves multiple functions: it provides constant current control for LED strings through the power transistor and rectifying transistor, generates supply voltage for the dimming controller through the inductor and rectifying transistor, and enables both dimming and color temperature regulation functions through the shared power supply, making the circuit multi-functional and reducing overall component count.
2Ease of operation
If additional power supply chip and voltage converter are used, then supply voltage for dimming controller is generated, but quantity of components increases
Solution Approach 1:
The patent merges the power supply chip and voltage converter functions into a single integrated power stage circuit. The inductor L1 and rectifying transistor QR1 in the power stage circuit serve dual purposes: controlling LED string current and generating supply voltage for the dimming controller, reducing the total number of components while maintaining ease of operation.
Solution Approach 2:
The power stage circuit components, particularly the inductor L1 and rectifying transistor QR1, perform multiple functions: they control the constant current for LED strings and simultaneously generate the supply voltage for the dimming controller through rectification and voltage regulation, eliminating the need for separate dedicated components for each function.
3Power
If separate power supply chip is used, then power conversion is achieved, but overall size increases
Solution Approach 1:
The patent combines the power conversion functions into a single integrated power stage circuit that handles both LED string power delivery and dimming controller power supply generation. The shared inductor L1 and rectifying transistor QR1 perform power conversion for both loads simultaneously, reducing the overall circuit size compared to separate power supply chips.
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 reduces the number of components and overall size, lowering product costs while maintaining effective constant current control and brightness adjustment for LED loads, and providing a supply voltage for dimming controllers or USB ports.
Implementation Method 1
a single inductor, which, during an on-time of a switch, charges a first capacitor with a bus voltage, and during an off-time of the switch, discharges the first capacitor through a power transistor, a rectifying transistor and the inductor
Implementation Method 2
receive a current signal at an output terminal of the power stage circuit, and generate a constant signal by charging a capacitor in the constant voltage generating circuit with the current signal
Data Source
AI summary
The present disclosure relates to LED driving circuit and method using a single inductor. A constant current controller controls a power stage circuit to provide a constant output signal, and thus to provide a constant current signal for an LED load. A dimming controller regulates luminance of the LED load. A constant voltage generating circuit receives the current signal at an output terminal of the power stage circuit and a reserve supply voltage for providing a supply voltage for the dimming controller. Compared with the prior art, the present disclosure does not need an independent power supply chip, and reduces components such as inductors and rectifying transistors. Thus, a peripheral circuit is simplified, and an overall size of the system is reduced.