Single Inductor LED Driver Circuit for Cost Reduction
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Solution Overview
Problem
Conventional LED driving circuits are complex and costly due to the need for multiple chips and inductors, requiring additional power supply chips for dimming controllers, which increases product cost and complexity.
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 for LEDs and a reserve supply voltage for dimming controllers or USB ports without an additional power supply chip, simplifying the peripheral circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional LED driving circuit uses separate power supply chips for constant current control and dimming controller power supply, then reliable power supply is achieved, but device complexity and product cost increase
Solution Approach 1:
The patent combines the constant current control function and constant voltage generation function into a single integrated chip. The chip includes a power stage circuit with BUCK converter for constant current control, and a constant voltage generating circuit with separate switch and inductor for generating supply voltage for the dimming controller. This integration eliminates the need for separate power supply chips while maintaining reliable power supply for both LED driving and controller operations.
Solution Approach 2:
The integrated chip performs multiple functions: it provides constant current control for LED strings, generates constant voltage for the dimming controller, and can simultaneously power both the LED load and the control circuitry. The power stage circuit and constant voltage generating circuit share the same chip resource, enabling one chip to serve multiple purposes that previously required separate components.
2Reliability
If additional power supply chips are used for dimming controller, then adequate power supply is ensured, but manufacturing cost increases
Solution Approach 1:
The patent merges the constant current control chip and the constant voltage power supply chip into a single integrated chip. This eliminates the need to purchase, stock, and assemble multiple separate chips, directly reducing manufacturing costs while ensuring adequate power supply through the integrated power stage circuit and constant voltage generating circuit.
3Power
If multiple inductors are used in the circuit, then power conversion efficiency is maintained, but component quantity and circuit complexity increase
Solution Approach 1:
The patent designs the power stage circuit and constant voltage generating circuit to share the same inductor L1. The power stage circuit uses L1 for BUCK conversion to generate constant current, while the constant voltage generating circuit also uses L1 to generate supply voltage for the dimming controller. This shared inductor approach reduces component quantity from two inductors to one, simplifying the circuit while maintaining power conversion efficiency through proper circuit design.
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 solution reduces component count, simplifies the circuit, and lowers production costs by eliminating the need for extra chips and inductors, while maintaining constant current control and brightness adjustment for LED loads.
Implementation Method 1
a BUCK converter including switches QM1, QR1 and an inductor L1
Implementation Method 2
generate a constant voltage signal Vout2 through a BUCK converter including switches QM2, QR2 and an inductor L2. The constant voltage signal Vout2 is used for dimming controller MCU
Data Source
AI summary
The present disclosure relates to an 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.