LED Driving Circuit Stability via Variable Resistor Mediator
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Solution Overview
Problem
Existing LED driving devices experience instability in output voltage, which can lead to sudden changes and erroneous activation of protection functions, affecting the stability of the power supply circuit and display performance in high-end display applications.
Innovation Solution
A light-emitting diode driving system that includes a power supply circuit, a current source, a comparator, and a control logic circuit with a variable resistor circuit to adjust the output voltage smoothly by comparing voltages and generating feedback signals, preventing sudden changes in output voltage and avoiding erroneous protection function activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the LED driving device directly transmits the output signal to the power supply circuit, then the LED can be driven simply, but the output voltage increases quickly in a short time causing instability in the power supply circuit
Solution Approach 1:
A variable resistor circuit is introduced as an intermediary component between the driving device and power supply circuit. This circuit dynamically adjusts the resistance value based on the output signal, thereby controlling the rate of voltage increase and preventing sudden voltage changes that would destabilize the power supply circuit.
Solution Approach 2:
The resistance value of the resistor circuit is made variable rather than fixed. The resistance dynamically changes in response to the output signal from the driving device, allowing the system to adaptively control the voltage rise rate and maintain power supply circuit stability during operation.
2Speed
If the output voltage increases quickly, then the LED brightness can be adjusted rapidly, but the protection function is erroneously enabled
Solution Approach 1:
The variable resistor circuit serves as a mediator that decouples the rapid brightness adjustment capability from the protection function trigger. By controlling the rate of voltage increase through dynamic resistance adjustment, it allows fast brightness changes while preventing the voltage from reaching thresholds that would erroneously activate protection functions.
Solution Approach 2:
The system performs preliminary action by proactively adjusting the resistance value before sudden voltage changes can occur. The variable resistor circuit anticipates the voltage increase and modulates the resistance in advance to control the voltage rise rate, preventing erroneous protection activation before it can happen.
Data Source
AI summary
A light-emitting diode driving system including a load, a power supply circuit and a light-emitting diode driving device is provided. The load includes one or more light-emitting diode strings. The power supply circuit outputs an output voltage to drive the load according to a feedback signal. The light-emitting diode driving device includes at least one current source, at least one comparator and a control logic circuit. The current source outputs a current to drive the load. The comparator compares a first voltage from the current source to a reference voltage and outputs a second voltage according to a comparison result. The control logic circuit includes a control node. The control logic circuit receives the second voltage through the control node and converts the second voltage to a control signal to adjust a resistance value of a variable resistor circuit. A light-emitting diode driving device is also provided.