Magnetic Sensor IC Self-Test via Fault Pin
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Solution Overview
Problem
In safety-critical applications like automobiles, there is a lack of effective test modes to ensure magnetic sensor integrated circuits (ICs) are functioning properly after installation, particularly in scenarios where a linear magnetic sensing element may fail, posing a dangerous situation.
Innovation Solution
A self-test feature for magnetic position sensing ICs using a fault pin in a linear Hall effect sensor for current sensing applications, which allows for manual or automatic invocation of a test mode to validate the IC's operation, including fault detection modules with programmable window comparators to identify current levels above or below thresholds, and output signals indicating pass/fail results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If test modes are implemented for magnetic sensor ICs, then functional safety and reliability are improved, but device complexity increases
Solution Approach 1:
The patent combines the self-test functionality with the existing fault detection module and output pin structure. The self-test mode utilizes the same fault pin (pin 4) that is already dedicated for fault indication, merging testing functionality with existing diagnostic infrastructure rather than adding separate dedicated test pins or circuits.
Solution Approach 2:
The fault pin serves multiple functions: it indicates fault conditions during normal operation and simultaneously serves as the interface for initiating and receiving self-test results. This multi-functionality reduces the need for additional dedicated test pins, thereby limiting the increase in device complexity while maintaining comprehensive testing capability.
2Reliability
If self-test functionality is added to fault detection modules, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The self-test circuitry is integrated within the existing fault detection module structure. The test mode utilizes the same comparator circuits and output pin infrastructure already present in the device, combining testing functionality with existing manufacturing processes rather than requiring separate dedicated test circuit fabrication.
3Measurement precision
If the self-test is terminated when a magnetic field above flux threshold is detected, then measurement precision is maintained, but test duration may be reduced
Solution Approach 1:
The system performs preliminary checking of magnetic field conditions before completing the full self-test sequence. If a magnetic field above the flux threshold is detected during testing, the self-test is terminated early, avoiding unnecessary testing under conditions that would compromise measurement precision while reducing overall test duration.
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
Enhances functional safety by enabling reliable testing of ICs in current sensing applications, preventing damage to control electronics by shutting off current sources when magnetic fields exceed thresholds, and improving overall system reliability in safety-critical environments.
Implementation Method 1
A current sensor IC 100 includes a Hall element 104 disposed within a core 200
Data Source
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AI summary
Integrated circuit (100) having a magnetic sensing element (104), a fault detection module including circuitry (102) to detect a fault condition and to self-test operation of the circuitry to detect the fault. The integrated circuit includes a fault pin to indicate the fault condition.