LED Driver Short Circuit Protection via Voltage Sampling
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Solution Overview
Problem
Existing LED driver circuits lack effective short circuit protection, leading to damage of switch components due to over-voltage, static, and high temperature, resulting in burned LEDs.
Innovation Solution
An LED driver circuit with short circuit protection is designed, incorporating a power module with constant voltage capability, a controlling module, a sampling module, and a switch controlling module that reduces or cuts off output voltage during a short circuit, using N-channel and P-channel metal oxide semiconductor switches and resistors to sample voltage signals and control the second switch to prevent excessive current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the switch Q1 is frequently turned on or off to control LED current, then the LED can be dimmed without impairing useful life, but the switch is vulnerable to damage from over-voltage, static, and high temperature resulting in short circuit
Solution Approach 1:
The protection circuit is activated before the switch Q1 fails. The sampling module continuously monitors the voltage across Q1, and when abnormal conditions are detected (indicating potential failure), the controlling module preemptively adjusts the switch state to prevent complete breakdown and short circuit, thereby protecting both the switch and extending LED operational life
Solution Approach 2:
The sampling module provides real-time feedback on the voltage status of switch Q1 to the controlling module. This feedback mechanism allows the system to monitor switch health continuously and automatically adjust operation to prevent failure, resolving the contradiction between frequent switching for dimming and maintaining switch reliability
2Ease of operation
If the switch Q1 fails and loses switch function, then the circuit becomes a direct wire connection, but this causes short circuit and burns the LED due to excessive current
Solution Approach 1:
The protection circuit applies preliminary anti-action by detecting abnormal voltage conditions across switch Q1 before complete failure occurs. When the sampling module detects that the voltage across Q1 exceeds safe thresholds, the controlling module immediately takes corrective action to prevent the switch from becoming a failed wire connection, thereby preventing the harmful short circuit condition before it can damage the LED
Solution Approach 2:
The sampling module and controlling module act as intermediary protective elements between the switch Q1 and the LED. When Q1 fails, this intermediary protection circuit detects the failure condition and intervenes to prevent excessive current from reaching the LED, thus resolving the contradiction between maintaining circuit continuity and preventing current-induced damage
Data Source
AI summary
An LED driver having short circuit protection includes a power, a controlling module coupled to the power and be configured to control output thereof, a sampling module electrically connected to the controlling module, a switch controlling module coupled to the sampling module, and a second switch coupled to the switch controlling module 40 and the output end of the power. The controlling module includes a first switch. The sampling module gets a low level signal during that short circuit is occurred in the first switch. When the switch controlling module receives the low level signal, it turns off the second switch so as to reduce the input voltage of the controlling module. The LED driver having short circuit protection can protect the first switch and load during that short circuit is occurred in the first switch.