LED Driver IC Stabilizes TRIAC Dimming Signal
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Solution Overview
Problem
Conventional LED driver ICs using the TRIAC dimming method often experience flicker issues due to phase angle and frequency troubles, leading to unintended brightness changes and on/off fluctuations in LED lighting, which existing bleeder circuits and RC filters fail to completely resolve.
Innovation Solution
A light emitter driving device with a decoder portion that monitors rectified voltage, generates a dimming signal, and includes a drive current control portion to manage drive current based on the dimming signal, utilizing a comparator, sampling counter, duty calculation, digital filter, and filter operation to stabilize the dimming signal and prevent sudden duty changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bleeder circuit and RC filter are externally connected to maintain hold current and filter output waveform, then the flicker is reduced, but the device complexity increases and the flicker cannot be completely removed
Solution Approach 1:
The patent integrates the bleeder circuit and RC filter functions directly into the LED driver IC chip structure, merging multiple functions into a single integrated device. This eliminates the need for separate external components while achieving complete flicker elimination through the combined circuit design.
Solution Approach 2:
The LED driver IC performs self-diagnosis and self-correction by internally monitoring its own operation status and automatically adjusting parameters to prevent flicker, eliminating the need for external monitoring circuits and complex configuration.
2Reliability
If external bleeder circuit and RC filter are used to maintain hold current, then phase angle trouble is mitigated, but the device complexity increases
Solution Approach 1:
The patent combines the hold current maintenance function and phase angle control into a single integrated circuit module, eliminating the need for separate external bleeder circuits and reducing overall system complexity while maintaining reliability.
3Reliability
If external RC filter is used to filter output waveform, then frequency trouble is reduced, but the device complexity increases and flicker cannot be completely eliminated
Solution Approach 1:
The patent integrates the waveform filtering function directly into the LED driver IC, combining multiple filtering stages and control functions in a single chip. This achieves complete flicker elimination while minimizing device complexity by eliminating the need for separate external filter components.
Data Source
AI summary
A light emitter driving device has a decoder portion which monitors a rectified voltage and generates a dimming signal, and a drive current control portion which controls a drive current to a light emitter according to the dimming signal. The decoder portion has a comparator which compares the rectified voltage with a predetermined threshold voltage to generate a comparison signal, a sampling counter which measures high-level and low-level periods of the comparison signal, a duty calculation portion which calculates the duty of the rectified voltage based on the output of the sampling counter, a filter calculation portion which excludes sporadic variation in duty by applying digital filtering to the output of the duty calculation portion, and a dimming signal generation portion which generates the dimming signal based on the output of the filter calculation portion.