LED Power Supply Stabilization via Dual Feedback Control
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Solution Overview
Problem
Conventional power supply systems for small-sized information terminals, such as cellular phones, face instability due to variable output voltages when the LED is switched off, affecting other circuits like short-circuit detection and protection circuits.
Innovation Solution
A power supply apparatus with dual feedback paths and a control circuit that stabilizes the driving voltage by adjusting one of the feedback voltages closer to a predetermined reference voltage, ensuring stability even when the load state changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single feedback path is used to control the booster circuit, then the circuit structure is simple, but the output voltage becomes variable when the load state changes, causing circuit instability
Solution Approach 1:
The feedback circuit is segmented into two independent feedback paths: a first feedback path that feeds back a first voltage from the output terminal, and a second feedback path that feeds back a second voltage from the connection point between the current driving circuit and the load. This segmentation allows each path to independently monitor different voltage points, ensuring stable operation under various load conditions without increasing overall circuit complexity.
Solution Approach 2:
The invention implements dual feedback mechanisms where the control circuit receives both first feedback voltage and second feedback voltage, and controls the voltage generation unit to maintain one of these voltages closer to a predetermined reference voltage. This feedback control ensures stable driving voltage even when load state changes, preventing circuit instability.
2Use of energy by moving object
If the LED is switched off, then power consumption is reduced, but the output voltage becomes variable which may influence other circuits such as short-circuit detection and protection circuits
Solution Approach 1:
The second feedback path is established in advance, connecting to the point between the current driving circuit and the load before the LED switches off. This preliminary arrangement ensures that when the LED is off, the second feedback voltage remains stable and can be used by the control circuit to maintain stable output voltage, preventing interference with short-circuit detection and protection circuits while still allowing power reduction.
3Stability of the object's composition
If the output voltage is kept constant by holding electric charges in the output capacitor, then the voltage stability is improved, but the circuit cannot adapt to load state changes
Solution Approach 1:
The invention dynamically switches between two feedback modes based on load conditions. The control circuit monitors both first feedback voltage and second feedback voltage, and adaptively controls the voltage generation unit to maintain the appropriate voltage closer to the reference voltage. This dynamic adaptation allows the circuit to maintain stability while responding to load state changes, including the transition when LED is switched off.
Data Source
AI summary
A voltage generation unit generates a driving voltage for driving an LED. A first feedback path feeds back a voltage according to a voltage at one end of the LED. A second feedback path feeds back a voltage according to a voltage at the other end of the LED. A current driving circuit is provided on a path on which the voltage generation unit drives the LED. A control circuit controls the voltage generation unit so that one of first and second feedback voltages fed back by the first and second feedback paths, respectively is closer to a predetermined reference voltage.