LED Driver Fault Detection IC for Off-Chip Protection
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Solution Overview
Problem
Traditional on-chip LED short and open circuit protections are inadequate for addressing manufacturing defects and degradation in off-chip MOSFETs, LED current sensing resistors, and other components, particularly in high-current LED arrays used in three-dimensional televisions and displays, where shorts can cause overheating and additional failures.
Innovation Solution
A fault detection IC with integrated circuits for detecting LED short faults, open faults, MOSFET short faults, sense resistor short faults, sense resistor open faults, and unused LED channels, capable of operating in both calibration and real-time modes, using voltage dividers, comparators, and decoders to identify faults and prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple fault detection circuits are integrated into a single IC, then device complexity is reduced and manufacturing cost is lowered, but the ability to detect specific faults in off-chip components may be compromised
Solution Approach 1:
The fault detection IC is divided into multiple independent detection circuits, each responsible for detecting specific fault types (LED short, LED open, MOSFET short, sense resistor faults). This segmentation allows comprehensive fault coverage while maintaining modular design that reduces overall system complexity.
Solution Approach 2:
A single fault detection IC integrates multiple detection functions that can identify various faults across different off-chip components. The IC serves universal purposes by combining LED fault detection, MOSFET fault detection, and sense resistor fault detection in one device, reducing the need for multiple separate detection circuits.
2Temperature
If heat-producing components are moved off-chip to address thermal issues and reduce IC cost, then thermal management is improved and IC cost is reduced, but fault detection and protection capabilities are weakened
Solution Approach 1:
The fault detection IC acts as an intermediary between the control system and the off-chip power components (MOSFETs, sense resistors). It monitors these external components for faults and provides protection signals, enabling thermal management benefits of off-chip placement while maintaining reliability through continuous external monitoring.
Solution Approach 2:
The detection circuits continuously monitor off-chip components for fault conditions before these faults can cause catastrophic failure. By detecting faults preliminarily and generating protection signals, the system prevents damage to LEDs and power components, maintaining reliability even with heat-producing components placed off-chip.
3Reliability
If comprehensive fault detection circuits are implemented, then reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
Multiple fault detection circuits are merged into a single integrated IC, combining LED short detection, LED open detection, MOSFET short detection, and sense resistor fault detection. This merging reduces the number of separate components needed while providing comprehensive fault coverage, improving reliability without proportionally increasing overall system complexity.
Data Source
AI summary
The embodiments disclosed herein describe a set of fault detection circuits for LED circuits in an LED channel. A first fault detection circuit is configured to detect a short fault across one or more LEDs. A second fault detection circuit is configured to detect an open fault across an LED. A third fault detection circuit is configured to detect a short across an LED channel transistor. A fourth fault detection circuit is configured to detect an LED channel sense resistor open fault. A fifth fault detection circuit is configured to detect if the LED channel is being intentionally unused. These fault detect circuits can be implemented in a fault detection integrated circuit coupled to the LED channel.