PWM Signal Conversion Circuit for Capacitor-Free LED Dimming
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing LED dimming systems face challenges in converting PWM signals into analog signals due to the need for large capacitors, which are difficult to integrate and increase complexity and cost.
Innovation Solution
A PWM signal conversion circuit and method that includes a detection module, addition module, switch signal generation, duty cycle ratio generation, and output voltage generation to extract the duty cycle ratio of low-frequency PWM signals without large capacitors, allowing integration within a chip and simplifying the peripheral circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a low-pass filter with a large-capacity capacitor is used to convert PWM signal to analog signal, then the filtering effect is improved, but the device complexity and integration difficulty increase
Solution Approach 1:
The patent replaces the traditional RC low-pass filter (analog filtering mechanism) with a digital sampling and calculation system. The PWM signal is sampled by detecting rising and falling edges, and the duty cycle is calculated through digital operations (addition, multiplication, and division) to generate the analog output voltage. This substitution eliminates the need for large-capacity capacitors and complex analog filtering circuits.
Solution Approach 2:
The patent introduces an intermediary calculation process between the PWM signal input and the analog output. Instead of directly filtering the PWM signal, the system first samples the signal edges, calculates the duty cycle ratio through digital operations, and then generates the output voltage based on this calculated ratio. This intermediary digital calculation approach simplifies the overall circuit structure while maintaining signal conversion accuracy.
2Measurement precision
If digital sampling techniques with division operation are used to obtain duty cycle, then the conversion accuracy is improved, but the implementation complexity increases
Solution Approach 1:
The patent segments the duty cycle calculation process into distinct functional modules: edge detection unit for sampling, addition unit for accumulating clock cycles, multiplication unit for scaling, and division unit for calculating the duty cycle ratio. This segmentation allows each module to perform a specific function with optimized complexity, making the overall implementation more manageable and manufacturable while maintaining high measurement accuracy.
Data Source
AI summary
A PWM signal conversion circuit and method, and an LED dimming system. The circuit includes: a PWM signal detection module, which outputs a first voltage corresponding to a low-level time of the PWM signal and a second voltage corresponding to a high-level time of the PWM signal; an addition module, which sums the first and second voltages to obtain a third voltage; a switch signal generation module, which generates a switch signal based on the third voltage; a duty cycle ratio generation module, which obtains a duty cycle ratio of the PWM signal based on a counting to the high level of the PWM signal by the switch signal; and an output voltage generation module, which obtains an output voltage related to a duty cycle of the PWM signal based on the duty cycle ratio.