LED Power Supply Dimming Feedback Circuit
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Solution Overview
Problem
Conventional LED power supply apparatuses require additional sense circuits and voltage conversion circuits to control brightness, which complicates the structure and functionality.
Innovation Solution
A power supply apparatus with a dimmer, a converter, and a dimming feedback unit that includes an amplifier and resistors/capacitors to control the duty of the switch based on feedback voltage, eliminating the need for a sense circuit to detect dimming angles and fluctuate reference voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a sense circuit and voltage conversion circuit are added to control LED brightness, then the brightness control function is improved, but the circuit structure becomes complex
Solution Approach 1:
The patent extracts the brightness control function from the conventional complex circuit structure by removing the sense circuit and voltage conversion circuit. Instead, it directly utilizes the dimmer's output voltage to control the PWM duty cycle, achieving brightness control with a simplified circuit architecture that maintains the essential function while eliminating unnecessary components.
Solution Approach 2:
The patent makes the dimmer serve multiple functions: it not only provides power regulation but also directly provides the control signal for PWM dimming. The feedback unit uses the dimmer's output voltage itself as the feedback signal, eliminating the need for separate sense circuits and achieving both power control and brightness control through a single component.
2Measurement precision
If a sense circuit is used to detect dimming angles, then the dimming control precision is improved, but the device complexity increases
Solution Approach 1:
The patent implements self-service by using the dimmer's own output voltage as the feedback signal for control. The feedback unit directly monitors the dimmer's output and uses this signal to adjust the PWM duty cycle, eliminating the need for external sense circuits to detect dimming angles. The system serves itself by using its own operational parameters for control feedback.
3Adaptability or versatility
If the reference voltage is fluctuated to control output current, then the brightness control is improved, but the circuit functionality becomes complex
Solution Approach 1:
Instead of fluctuating the reference voltage to control output current as in conventional designs, the patent inverts the approach by using the dimmer's output voltage directly as the control signal. The feedback unit compares the dimmer's output voltage with a stable reference voltage and adjusts the PWM duty cycle accordingly, achieving current control through duty cycle modulation rather than reference voltage fluctuation.
Data Source
AI summary
A power supply apparatus and a driving method thereof are disclosedThe power supply apparatus includes: a dimmer controlling externally input power; a converter including a switch, and converting an output of the dimmer according to a duty of the switch and supplying a first current to a load; a dimming feedback unit receiving a first voltage corresponding to the first current, and having a finite gain in a DC state; and a controller controlling the duty of the switch according to an output of the dimming feedback unit. A duty of the switch is controlled according to an output of such a dimming feedback unit so that a dimming operation is performed.