AC LED Driver with Chip-to-Chip Voltage Feedback

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Solution Overview

Problem

Conventional AC drives for LEDs fail to achieve ultra-low flicker while maintaining triac dimming performance and power line regulation, often resulting in non-uniform light due to inadequate control of LED current.

Innovation Solution

An AC direct drive system with chip-to-chip communication for monitoring and regulating input voltage, allowing for amp-second balance and reduced capacitance, ensuring low ripple performance and improved light uniformity across multiple drive stages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional AC drives are used for LEDs, then power line regulation is achieved, but flicker exceeds 5% and light uniformity deteriorates

Engineering Contradiction:

Improvepower line regulationVSAvoidflicker

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where the first current controller monitors input voltage and communicates with the second current controller to adjust LED current accordingly. This closed-loop control ensures that LED current is regulated based on actual input voltage conditions, maintaining constant current control and reducing flicker to below 5% while preserving power line regulation capability.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts LED current based on real-time input voltage monitoring. The first current controller continuously monitors input voltage and communicates voltage information to the second current controller, which then dynamically adjusts the LED current to compensate for voltage fluctuations, achieving both flicker reduction and power line regulation.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If conventional AC drives are used for LEDs, then triac dimming is implemented, but light uniformity across multiple drive stages deteriorates

Engineering Contradiction:

Improvetriac dimmingVSAvoidlight uniformity

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent divides the LED lighting system into multiple independently controllable drive stages, each with its own current controllers. The first current controller segments the control function by monitoring input voltage and communicating with second current controllers at different drive stages. This segmentation allows each stage to be precisely controlled based on actual voltage conditions, maintaining light uniformity across all stages while preserving triac dimming capability.

Inventive Principle:

Principle #1Segmentation

3Device complexity

If inadequate LED current control is used, then device complexity is reduced, but light uniformity and flicker performance deteriorate

Engineering Contradiction:

Improvecontrol circuitryVSAvoidflicker

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary communication mechanism between the first current controller and the second current controller. The first current controller acts as an intermediary that monitors input voltage and transmits this information to the second current controller, which then adjusts LED current accordingly. This intermediary approach enables sophisticated current control and flicker reduction without requiring overly complex circuitry at each individual stage.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10426008B2AC direct drive system for light emitting diodes with ultra-low flicker, low harmonic distortion, dimming compatibility and power line regulation

Publication Date: 2019.09.24 EXAR CORP

AI summary

As a non-limiting example, various aspects of this disclosure provide embodiments of AC direct drives for light emitting diodes for a wide variety of drive stages.