LED Current Supply Circuit with Trimmer Resistor

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Solution Overview

Problem

Existing LED power supply circuits, or LED drivers, are limited in their ability to adjust the supply current intensity, often requiring significant hardware and software efforts or restricting current selection to discrete levels.

Innovation Solution

A circuit with an electronic ballast and a trimming resistor allows for adjustable current intensity by connecting the resistor in parallel between two of the ballast's connection terminals, enabling continuous adjustment between predefined current levels without modifying the ballast itself.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a power supply circuit arrangement with multiple terminals is used to deliver specific current values, then discrete current levels can be provided, but the supply current can only be selected from a limited number of fixed current values

Engineering Contradiction:
Improvecurrent selection flexibilityVSAvoiddriver arrangement complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

A trimmer resistor is introduced as an intermediary component between the power supply circuit and the LED. This trimmer resistor allows continuous adjustment of the supply current by varying its resistance value, enabling fine-tuning between the fixed current levels provided by the multiple terminals without requiring complex driver modifications

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the resistance parameter of the trimmer resistor to adjust the supply current. By varying the resistance value of the trimmer resistor, the current supplied to the LED can be continuously adjusted, transforming the discrete current selection into a continuous adjustable parameter

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If software interface is equipped to electronically adjust power source, then current can be freely adjusted, but significant effort is required on hardware and software sides

Engineering Contradiction:
Improvecurrent adjustment flexibilityVSAvoidhardware and software effort
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention extracts the current adjustment function from the complex software-controlled power supply system and implements it through a simple passive trimmer resistor. This removes the need for software programming and complex hardware modifications while maintaining current adjustment capability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The trimmer resistor is a simple, inexpensive passive component that provides the adjustment function without requiring expensive software licenses, complex control circuits, or ongoing software maintenance. It is a straightforward hardware solution that replaces complex software-controlled systems

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If DIP switches or wire jumpers are equipped to select current levels, then discrete current levels can be selected, but only a limited number of discrete current levels can be selected

Engineering Contradiction:
Improvecurrent level selectionVSAvoidnumber of selectable current levels
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The invention replaces static discrete current selection (DIP switches or wire jumpers) with a dynamic continuous adjustment mechanism. The trimmer resistor can be varied continuously to provide any current level within the operating range, transforming the static selection into a dynamic adjustable parameter

Inventive Principle:
Principle #15Dynamics

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 allows for easy and flexible adjustment of the current intensity for LEDs, overcoming the limitations of discrete current settings in prior art, while maintaining a constant current source to accommodate various LED configurations and aging effects.

Implementation Method 1

a trimmer resistor is further provided which is connected in parallel to two of the second terminals in order to adjust the selected supply current

Methodology Applied
Scientific EffectElectrical Resistance: Electrical Resistance

Data Source

PatentEP2897444B1Circuit for LED current supply
Publication Date: 2020.08.26 SITECO GMBH
  • EP2897444B1 patent drawingFigure 1a~1b
  • EP2897444B1 patent drawingFigure 2~3
  • EP2897444B1 patent drawingFigure 4~6

AI summary

The invention relates to a circuit for supplying power to an LED, comprising the following: an electrical ballast for connecting an arrangement of at least one LED, wherein the electronic ballast has a first terminal to which the arrangement of at least one LED is connected with an electrode, preferably the anode, and several second terminals to which the arrangement of at least one LED can be selectively connected with the second electrode, preferably the cathode, in order to supply the at least one LED with a current corresponding to one of the selected second terminals, wherein a trim resistor is provided which is connected in parallel to two of the second terminals in order to adjust the selected supply current.