SEL Detection Circuit Using Current Rate Monitoring
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Solution Overview
Problem
Conventional single-event latch-up (SEL) detection and protection circuits for CMOS ICs in space applications are inadequate due to challenges in setting appropriate threshold currents, leading to false triggering and failure to detect micro latch-ups, which can result in permanent damage.
Innovation Solution
An electronic circuit that detects both absolute load current and its rate of change, comparing them with respective thresholds to trigger power shutdown, allowing for earlier detection and quicker response to SEL events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the threshold current is set much higher than nominal current to avoid false triggering, then false triggering is avoided, but the target ICs may inadvertently be subjected to a large SEL current for an extended period before protection is triggered
Solution Approach 1:
The system performs preliminary detection by monitoring both absolute current and current change rate continuously. When a rapid current change is detected, the system is already in an alert state and can trigger protection immediately, eliminating the delay associated with waiting for current to reach a high threshold level.
Solution Approach 2:
The dual-detector system provides continuous feedback on both absolute current levels and current change rates. This feedback mechanism enables real-time monitoring and immediate response to latch-up conditions, allowing the system to maintain high threshold settings for false triggering prevention while still achieving rapid protection response through change rate detection.
2Device complexity
If a conventional over-current protection circuit is used, then the circuit structure is simple, but it cannot detect micro latch-up events that dissipate at localized low current
Solution Approach 1:
The detection function is segmented into two independent detectors: one for absolute current level and another for current change rate. This allows each detector to be optimized for its specific function, enabling detection of micro latch-up events through rapid current changes even when absolute current remains below the high threshold setting.
Solution Approach 2:
The invention adds a new detection dimension by monitoring the rate of change of current (di/dt) in addition to the traditional absolute current level. This temporal dimension enables detection of latch-up events based on how quickly current changes, providing an alternative detection criterion that works even when absolute current thresholds are set high to avoid false triggering.
Data Source
AI summary
An electronic circuit for single-event latch-up (SEL) detection and protection of a target integrated circuit (IC) is disclosed. The circuit comprises: a first detector configured for detecting an absolute load current (i) and comparing the absolute load current (i) with a threshold current (ith); a second detector configured for detecting a rate of change of load current (di/dt) and comparing the rate of change of load current (di/dt) with a threshold current change rate (di/dt)th; and a determination module for triggering a power shut-down to the target IC if the absolute load current (i) exceeds the threshold current (ith) and/or the rate of change of load current (di/dt) exceeds the threshold current change rate (di/dt)th.