LED Driver Protection Circuit Using Shared Inductor
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Solution Overview
Problem
Traditional overvoltage protection circuits in LED lighting are complex, leading to additional power loss and resonance issues when combined with dimming circuits, limiting their universality and efficiency.
Innovation Solution
A protection circuit comprising a detection module, trigger module, and locking module is integrated into the DC/DC conversion circuit, which detects output voltage, generates a trigger signal for overvoltage conditions, and stops the high-frequency switch from operating, preventing power loss and resonance in the dimming circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional overvoltage protection circuit is used, then overvoltage protection function is achieved, but the circuit complexity increases and additional power loss occurs
Solution Approach 1:
The protection circuit is merged with the existing DC/DC conversion circuit by utilizing the same inductor (first inductor) for both power conversion and voltage detection. The detection module shares the inductor structure with the conversion circuit, eliminating the need for separate detection components and reducing overall circuit complexity while maintaining overvoltage protection functionality.
Solution Approach 2:
The first inductor serves multiple functions: it acts as the energy storage element in the DC/DC conversion circuit and simultaneously serves as the detection element for overvoltage protection. This multi-functional design reduces the total component count and simplifies the circuit structure while achieving reliable overvoltage protection.
2Reliability
If a traditional overvoltage protection circuit is used, then overvoltage protection function is achieved, but additional power loss occurs due to continuous current flow
Solution Approach 1:
The protection circuit operates periodically rather than continuously. The detection module only activates when voltage conditions trigger the comparison operation, and the switching element operates in periodic pulses during normal conversion cycles. This periodic operation eliminates continuous current flow through the protection circuit components, significantly reducing power loss while maintaining protection capability.
Solution Approach 2:
The protection function is extracted as a separate modular detection and control system that operates independently from the main power conversion path. The detection module monitors voltage without drawing continuous current, and the switching element only engages when protection is needed, separating the protection function from continuous power flow and minimizing energy loss.
3Adaptability or versatility
If protection circuit is combined with dimming circuit, then brightness control is achieved, but resonance issues occur impacting dimming circuit universality
Solution Approach 1:
The detection module acts as an intermediary between the power conversion circuit and the control system. It monitors voltage conditions and provides feedback signals without directly interfering with the dimming control signals. This intermediary approach allows the protection circuit to operate independently from the dimming circuit, preventing resonance issues and maintaining compatibility with various dimming implementations.
Solution Approach 2:
The circuit is segmented into distinct functional modules: the DC/DC conversion module, the detection module, and the control module. Each module operates independently with clearly defined interfaces. The detection module monitors voltage without coupling into the dimming control path, and the switching element responds only to protection triggers, not dimming signals. This segmentation prevents unwanted interactions and resonance between protection and dimming functions, enhancing universality.
Data Source
AI summary
A protection circuit for an LED driver and a DC/DC converter. The LED driver includes a DC/DC converter and a protection circuit. The DC/DC converter is used to convert the input voltage of the DC voltage input terminal into an output voltage, which comprises a high frequency switch and an inductor. The protection circuit comprises a detection module, a trigger module and a locking module. The detection module is coupled to the inductor for detecting the output voltage and outputting the voltage detection signal. The trigger module is used to receive the voltage detection signal and output a voltage trigger signal when the voltage detection signal is a negative voltage and the absolute value of the negative voltage is greater than or equal to the preset value. The locking module is coupled to the trigger module and stops the high frequency switch from operating after receiving the voltage trigger signal.