LED Driving Device Overcurrent Protection Circuit
Solution Overview
Problem
Existing LED driving devices lack an effective overcurrent protection function, particularly when a power short circuit occurs at the cathode of the LED, leading to potential damage and instability in the light emitting device.
Innovation Solution
The proposed LED driving device incorporates a negative step-up/step-down DC/DC converter function, along with a protection circuit that detects overcurrents and automatically switches the switch Msw to an off-state when an overcurrent is detected, preventing damage and allowing for automatic recovery when the short circuit is released.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LED driving devices are used, then the device structure is simple, but the overcurrent protection function is insufficient when power short circuit occurs at the cathode
Solution Approach 1:
The patent combines the overcurrent protection function with the existing LED driving circuit by integrating a protection circuit that shares components with the driving circuit. The protection circuit utilizes the same switch Msw and incorporates additional detection circuitry that monitors current flow through the LED cathode, merging protection functionality into the existing device structure rather than adding completely separate protection components.
Solution Approach 2:
The patent implements a feedback mechanism where the protection circuit continuously monitors the current flowing through the LED cathode using a current detection resistor. When overcurrent is detected, the circuit generates a feedback signal that triggers the switch Msw to turn off, thereby protecting the LED. This feedback loop enables automatic protection without requiring external intervention or complex additional components.
2Reliability
If overcurrent protection is added to LED driving devices, then the protection function is improved, but the device complexity increases
Solution Approach 1:
The protection circuit is designed to perform multiple functions using a unified structure. The same switch Msw that controls the LED during normal operation also serves as the protection switch that disconnects the circuit during overcurrent conditions. The current detection resistor serves both as part of the normal current control circuitry and as the sensing element for overcurrent protection, reducing the need for separate dedicated protection components.
Solution Approach 2:
The protection circuit operates autonomously by automatically detecting overcurrent conditions and triggering the switch Msw to turn off without requiring external control or intervention. The circuit monitors itself through the current detection resistor and self-corrects by disconnecting the power supply when abnormal current flow is detected, enabling the device to protect itself using its own integrated components.
Data Source
AI summary
A light emitting element driving device is configured to drive a light emitting element, the light emitting element driving device includes: a switch driving unit configured to drive a switch connectable to a negative end of the light emitting element the positive end of which is grounded; and an overcurrent detection unit configured to detect an overcurrent based on a voltage generated across both ends of a current detection resistor connected to a negative side of the switch and the switch driving unit is configured to switch the switch to an off-state when the overcurrent detection unit detects the overcurrent.