LED Driver Dynamic Hysteresis Control for Deep Dimming
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing LED dimming technologies, such as PWM and analog dimming, face limitations in achieving deep dimming due to current ripples and EMI interference, and analog dimming's limited depth is restricted by maximum operating frequency or inductor current, affecting linearity.
Innovation Solution
An LED driver with a controller using current hysteresis control, where the hysteresis width varies with the dimming signal to generate a control signal, allowing for adjustable hysteresis width in the main circuit's back-end stage, enabling extended dimming depth and improved linearity across the entire dimming range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If PWM dimming is used to achieve deep dimming, then dimming depth is improved, but current ripple and EMI interference increase
Solution Approach 1:
The patent applies dynamics by making the hysteresis width adjustable rather than fixed. The controller dynamically adjusts the hysteresis width based on the dimming signal to achieve deep dimming while maintaining stable current output and reducing ripples. This dynamic adjustment allows the system to adapt to different dimming depths without generating excessive EMI interference or current ripple.
2Illumination intensity
If analog dimming is used for shallow dimming, then linearity is maintained, but dimming depth is limited by maximum operating frequency or inductor current
Solution Approach 1:
The patent applies parameter changes by varying the hysteresis width parameter in response to the dimming signal. This dynamic parameter adjustment allows the system to extend the analog dimming depth beyond the traditional limits imposed by maximum operating frequency or inductor current, while maintaining linearity through controlled current regulation.
3Illumination intensity
If fixed hysteresis width is used in current hysteresis control, then control simplicity is maintained, but dimming linearity and depth are limited
Solution Approach 1:
The patent transitions from a static fixed hysteresis width to a dynamic adjustable hysteresis width that responds to the dimming signal. This dynamic control enables extended dimming depth and improved linearity while the control mechanism remains integrated within the existing controller architecture, balancing performance improvement with acceptable control complexity.
Data Source
AI summary
The present disclosure discloses a light-emitting diode (LED) driver comprising a controller and a main circuit. The controller is configured to receive a dimming signal for dimming an LED load and use a current hysteresis control to generate a control signal, wherein a hysteresis width of the current hysteresis control varies with the dimming signal. The main circuit comprises a front-end stage configured to receive an AC input voltage and output a DC bus voltage, and a back-end stage configured to receive the bus voltage and responsive to the control signal, output a desired drive current through output terminals to the LED load so as to produce a target illumination intensity. The present disclosure widens the dimming depth of analog dimming in the LED dimming technology, achieves deep dimming and satisfies good dimming linearity in the entire dimming range.