Cloned Constant-Current LED Circuit for Scalable Multi-LED Driving
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Solution Overview
Problem
Existing LED products, particularly in automotive applications, often fail to provide constant current driving, leading to inferior performance, and existing solutions involving multiple ICs or specialized circuits are costly.
Innovation Solution
A low-cost electronic circuit design using integrated circuit controllers and low-cost commodity components to drive multiple LEDs with constant current, allowing for cloning of current paths to additional LEDs, compensating for temperature and voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple ICs or specialized circuits are used to drive multiple LEDs with constant current, then LED performance and reliability are improved, but product cost increases
Solution Approach 1:
The patent implements current cloning by copying the current from a reference LED through a transistor network. The collector current of the reference LED is replicated to multiple cloned LEDs via matched transistors, eliminating the need for multiple independent constant current sources. This achieves reliable constant current driving for multiple LEDs while using a single control IC, thereby reducing product cost.
Solution Approach 2:
The patent makes a single constant current source serve multiple functions by cloning the current to drive multiple LEDs simultaneously. The reference current path serves as a master that can be replicated to multiple slave paths, allowing one IC to control multiple LEDs with constant current, thus reducing the need for multiple specialized circuits.
2Reliability
If constant current driving is implemented for multiple LEDs, then optical and electrical design specifications are met, but circuit complexity increases
Solution Approach 1:
The patent segments the LED driving circuit into a reference current path and multiple cloned current paths. Each path is independently controllable through the transistor network, allowing precise control of current distribution. This segmentation enables compliance with optical and electrical specifications for each LED while maintaining a structured, manageable circuit architecture.
Solution Approach 2:
The patent employs feedback through the transistor base-emitter junctions to maintain constant current. The cloned transistors are configured such that their base voltages are derived from the reference path, creating a feedback mechanism that automatically adjusts current distribution to maintain constant current operation, ensuring specification compliance without complex control logic.
3Adaptability or versatility
If current is cloned to additional LEDs using additional components, then scalability is improved, but component count and cost increase
Solution Approach 1:
The patent merges multiple LED driving functions into a unified current cloning architecture. Instead of requiring separate constant current sources for each LED, the design combines them into a single reference path that clones current to multiple outputs through shared transistor components. This merging reduces the overall component count while maintaining scalability.
Solution Approach 2:
The patent uses current copying through matched transistor pairs to replicate the reference current to multiple LEDs. Each cloned LED path uses a copy of the reference transistor configuration, allowing scalable expansion where adding more LEDs simply requires adding more cloned transistor pairs rather than entire constant current source circuits.
Data Source
AI summary
A light emitting diode (LED) circuit is disclosed having an LED having a plurality of current paths. A controller may be included for controlling the LEDs. The LED is connected to a first transistor and a first current sink to drive a constant current through the LED through a first current path. At least one cloning transistor can establish a parallel current path through the LED and parallel to the first current path and is connected such that the constant current in the first current sink is duplicated in the parallel current path.