High-Side Switch Fault Detection via Turn-On Resistance Control
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Solution Overview
Problem
Existing switch devices face challenges in accurately distinguishing between load-open and short-to-power-supply-voltage conditions during the switch-on period of a high-side switch LSI, as both result in similar output voltage levels, making it difficult to determine the specific abnormal condition occurring.
Innovation Solution
A switch device with an output abnormality detection circuit that increases the turn-on resistance of the switch element and compares the output voltage with predefined voltages to determine whether a load-open or short-to-power-supply-voltage condition is present, using comparators and resistors to generate appropriate signals for differentiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the switch element is fully turned on to reduce resistance, then power loss is reduced, but the ability to detect abnormal conditions during the turn-on period is compromised
Solution Approach 1:
The output abnormality detection circuit performs abnormal condition detection during the turn-on period before the switch element is fully turned on. By detecting abnormalities in this preliminary phase, the system can identify issues before they affect full-power operation, thus maintaining both low power loss and reliable detection capability
Solution Approach 2:
The detection circuit monitors output current during the turn-on period and provides feedback about abnormal conditions. This feedback mechanism allows the system to detect abnormalities without preventing the switch from completing its turn-on sequence, thereby maintaining energy efficiency while enabling reliable fault detection
2Measurement precision
If the output current threshold is set low to detect abnormalities early, then detection sensitivity is improved, but false detection increases
Solution Approach 1:
The detection circuit uses multiple parameters including output current magnitude, turn-on resistance changes, and output voltage levels to determine abnormalities. By analyzing multiple parameters rather than relying solely on current threshold, the system achieves both high sensitivity and accurate distinction between different abnormal conditions
Solution Approach 2:
The detection method segments the abnormal condition detection into distinct phases: initial current threshold detection during turn-on, followed by turn-on resistance measurement, and finally output voltage comparison. This segmented approach allows each stage to contribute to overall detection accuracy without causing false positives
3Reliability
If the switch element is turned off completely to ensure safety, then safety is improved, but the time required for abnormal condition determination increases
Solution Approach 1:
The system performs preliminary abnormal condition detection during the turn-on period itself, before full operation begins. This preliminary detection eliminates the need for complete turn-off to assess safety, as abnormalities are already identified during the transition phase, thus maintaining safety without time loss
Solution Approach 2:
The detection circuit continuously monitors output parameters during the turn-on transition, maintaining detection capability throughout the entire turn-on sequence. This continuous monitoring ensures safety assessment occurs without interrupting the normal operation flow, minimizing determination time while maintaining safety
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables prompt and accurate determination of abnormal conditions, enhancing the safety and reliability of electronic devices by distinguishing between load-open and short-to-power-supply-voltage conditions without requiring the full turn-off of the switch, thus reducing the time taken for condition determination.
Implementation Method 1
a first comparator that compares an output current detection signal according to the output current or a sense voltage according to the output current with a predetermined threshold voltage to generate an output abnormality detection signal
Implementation Method 2
a second comparator that compares the output voltage with the first voltage to generate a turn-on resistance control signal
Implementation Method 3
a third comparator that compares the output voltage with the second voltage to generate a determination signal
Implementation Method 4
a first resistor coupled between the power supply terminal and an application node of the first voltage, a second resistor coupled between the power supply terminal and an application node of the second voltage, a first current source coupled between the application node of the first voltage and a constant electric potential node, and a second current source coupled between the application node of the second voltage and a constant electric potential node
Data Source
AI summary
Disclosed herein is a switch device including a switch element coupled between a power supply terminal and an output terminal, and an output abnormality detection circuit that. When an output current flowing during a turn-on period of the switch element is smaller than a threshold value, the output abnormality detection circuit detects an occurrence of an output abnormal condition, and increases a turn-on resistance of the switch element to determine which of a load-open condition and a short-to-power-supply-voltage condition is occurring at the output terminal on a basis of an output voltage at the output terminal.