Resettable Over-Current Protection Circuit for Lighting Devices
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Solution Overview
Problem
Current portable lighting devices face challenges with short-circuit protection mechanisms, such as fuses and comparator lockout protection circuits, which are inconvenient to repair, limited in application, and do not effectively prevent battery life reduction due to residual current.
Innovation Solution
A lighting device with a resettable over-current protection circuit, comprising a light source module, power supplying module, DC-to-DC converting module, over-current short-circuit protection module, reference voltage generating module, and self-locking protection module, which enables a self-locking protection mode to prevent fault expansion and maintain safety without reducing battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fuse is used for short-circuit protection, then the protection function is simple and reliable, but the device requires repair when the fuse melts
Solution Approach 1:
The protection circuit automatically resets itself after the fault is eliminated. The control unit monitors the current status and automatically restores normal operation without requiring manual intervention or repair, making the system self-service capable.
Solution Approach 2:
The patent replaces the mechanical fuse system with an electronic control system that uses electronic components (control unit, sensing elements) to detect and respond to overcurrent conditions, eliminating the need for physical fuse replacement.
2Reliability
If a comparator lockout protection circuit is used, then the protection can be repeatedly activated, but it cannot trigger protection when PWM duty cycle is very small and application is limited
Solution Approach 1:
The control unit is designed to detect overcurrent conditions regardless of PWM duty cycle magnitude. It monitors the actual current through sensing elements and triggers protection based on current magnitude rather than PWM signal characteristics, making it universally applicable across different operating conditions.
Solution Approach 2:
The patent replaces PWM-based protection triggering with direct current sensing using sensing elements that measure actual current flow. This substitution allows protection to be triggered based on real current conditions rather than signal characteristics, expanding applicability.
3Reliability
If a resettable fuse is used, then the protection function can be repeatedly activated, but residual current continues to flow after protection triggers
Solution Approach 1:
The control unit automatically monitors current conditions and manages the protection state. When overcurrent is detected, it triggers protection and maintains the blocked state until the fault is eliminated, then automatically resets. This self-managed approach ensures no residual current flows during protection periods.
Solution Approach 2:
The sensing elements continuously monitor current flow and provide feedback to the control unit. This feedback mechanism allows the control unit to detect when the fault condition has been eliminated and appropriately reset the protection circuit, ensuring current is fully stopped during protection and only restored when safe.
Data Source
AI summary
A lighting device having resettable over-current protection function includes a light source module, a power supplying module, a DC-to-DC converting module, an over-current short-circuit protection module, a reference voltage generating module and a self-locking protection module. The power supplying module generates an input voltage. The DC-to-DC converting module converts the input voltage into a driving voltage to drive the light source module. The over-current short-circuit protection module generates a voltage detecting by detecting a driving current passing through the light source module. The reference voltage generating module generates a reference voltage according to the input voltage and the voltage detecting signal. The self-locking protection module generates a control signal according to the input voltage and the reference voltage to turn off the over-current short-circuit protection module in order to perform a self-locking protection mode, such that the DC-to-DC converting module is disconnected from the light source module.