Frequency Compensation Control Circuit for LED Driver
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Solution Overview
Problem
Conventional illumination driving circuits cannot handle conditions of heavy line and light load, as the turn-on time required is often less than the minimum, leading to excessive current through light emitting diodes, which can cause them to burn out.
Innovation Solution
A control circuit with frequency compensation, comprising an oscillator, a first comparator, a second comparator, and a flip-flop, that automatically reduces the frequency of the oscillator's set signal when the sampling current exceeds the total voltage, preventing excessive current by adjusting the turn-on time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional illumination driving circuits are used, then the circuit can operate under normal conditions, but it cannot handle heavy line and light load conditions because the turn-on time is less than the minimum required, causing excessive current that burns out the light emitting diode
Solution Approach 1:
The control circuit dynamically adjusts the oscillation frequency based on the sampling current magnitude. When the current indicates heavy line and light load conditions, the frequency is automatically reduced to extend the turn-on time, ensuring it exceeds the minimum required time and preventing diode burnout while maintaining adaptability to varying load conditions
Solution Approach 2:
The circuit employs feedback mechanisms where the sampling current is continuously monitored and compared against reference voltages. This feedback loop enables the control circuit to detect heavy line and light load conditions and automatically adjust the oscillation frequency accordingly, ensuring reliable operation across different operating conditions
Data Source
AI summary
The present invention discloses a control circuit with frequency compensation, which can be applied to an open-loop control system. The control circuit includes an oscillator which is additionally connected to a first comparator including a first input end, a second input end and a first output end. The first input end provides for inputting a sampling current, the second input end provides for inputting a total voltage of a reference voltage and a DC-level voltage, and the first output end outputs a down-conversion signal. When the sampling current is larger than the total voltage, the first comparator will generate the down-conversion signal to the oscillator to reduce a frequency of the oscillator, such that a current of the open-loop control system can be controlled effectively to prevent an electronic element form being burned down.