Power Rail Fault Detection Using Fast Comparators and Counters
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Solution Overview
Problem
Existing power rail voltage monitoring systems in vehicles fail to accurately detect brief over-voltage and under-voltage events due to large measurement bandwidths and variable detection thresholds, leading to potential damage or operational issues in System-on-a-Chip (SoC) devices.
Innovation Solution
A power monitor system using fast analog comparators with programmable thresholds to digitally process over-voltage and under-voltage detections, incorporating a voltage fault detector and controller to generate interrupt and shutdown signals based on programmable counters and thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If slow deglitched-comparators are used to monitor power rail voltage, then false positive detections are reduced, but brief over-voltage and under-voltage events cannot be detected
Solution Approach 1:
The system divides the detection function into two separate components: a fast comparator that detects voltage events with high speed, and a slower deglitched-comparator that filters false positives. This segmentation allows each component to optimize for its specific function without compromise
Solution Approach 2:
A digital post-processing stage acts as an intermediary between the fast comparator and the final detection output. This intermediary processes the fast comparator's output through programmable thresholds and counters to eliminate false positives while preserving genuine events
2Speed
If fast analog comparators with large measurement bandwidths are used, then response speed is improved, but detection thresholds vary due to circuit noise causing false positive detections
Solution Approach 1:
The system implements feedback through programmable thresholds and counters that adjust the interpretation of comparator outputs. The digital post-processing stage uses feedback mechanisms to distinguish genuine voltage events from noise-induced false positives based on event duration and frequency patterns
Solution Approach 2:
The system uses dynamic, programmable thresholds rather than fixed thresholds. This allows the detection criteria to adapt to different operating conditions and noise levels, improving reliability while maintaining fast response capability
3Duration of action of stationary object
If periodic over-voltage and under-voltage events are monitored, then lifetime reduction of SoC devices can be detected, but slow comparators fail to capture these brief events
Solution Approach 1:
The fast comparator performs preliminary detection of voltage events before they complete. By capturing the event onset quickly and then using digital post-processing to determine if the event meets the criteria for lifetime impact, the system can detect brief events that would otherwise be missed
Data Source
AI summary
Power monitors, power supply circuits, and methods for operating a power supply. The method includes determining a voltage of a power rail provided to a load device from the power supply. The method also includes detecting that the voltage of the power rail is greater than or equal to an over-voltage threshold. The method further includes incrementing an over-voltage counter when the voltage of the power rail is detected as being greater than or equal to the over-voltage threshold. The method also includes detecting that the over-voltage counter is equal to a threshold value. The method further includes generating an interrupt signal when the over-voltage counter is detected as being equal to the threshold value.