Hysteretic LED Driver Feedback Loop for Current Precision
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hysteretic mode LED drivers suffer from comparator delay, leading to errors in the average value of the driving current, particularly exacerbated by steep slopes of the sensing signal, resulting in higher peak and average current values than ideal.
Innovation Solution
A feedback loop is introduced to sense the error between the average driving current and a target value, generating a feedback signal to adjust the reference signal or offset of the hysteretic comparing circuit, thereby reducing or eliminating the error and improving the precision of the average current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If hysteretic mode LED driver uses comparator to control average current, then fast response is achieved, but comparator delay causes error in average current precision
Solution Approach 1:
The patent introduces a feedback loop that senses the actual average driving current and compares it with the target average current. The feedback signal generated from this comparison is used to adjust the reference signal or offset of the hysteretic comparing circuit, thereby compensating for the comparator delay and improving the precision of the average current control while maintaining the fast response advantage.
2Speed
If steep slope sensing signal is used for fast control, then response speed improves, but comparator delay causes higher peak and average current values
Solution Approach 1:
The feedback loop senses the actual average driving current and generates a feedback signal to adjust the reference signal or offset of the hysteretic comparing circuit. This compensation mechanism counteracts the effects of comparator delay, ensuring that even with steep slope sensing signals for fast control, the peak and average current values remain precise and within the desired range.
Data Source
AI summary
A hysteretic mode LED driver for providing a driving current for an LED includes a hysteretic comparing circuit and a feedback loop. The hysteretic comparing circuit compares a driving current related sensing signal with a reference signal to control the average value of the driving current. The feedback loop senses the error between the average value of the driving current and a target value to adjust the reference signal or the offset of the hysteretic comparing circuit to adjust the average value of the driving current.