Magnetic Field Sensor Self-Test Circuit Design
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Solution Overview
Problem
Magnetic field sensors often fail due to manufacturing or design defects, and existing self-test capabilities are limited in effectiveness and efficiency, particularly in detecting failures during operation within complex systems like automotive control systems.
Innovation Solution
A magnetic field sensor with self-test capabilities that performs Built-In Self-Test (BIST) or Logical BIST (LBIST) tests, transmitting results on an output pin, and resumes normal operation after self-testing, using protocols like SENT, PWM, or triggered communications to detect and respond to signal interruptions, ensuring system reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-test capabilities are added to magnetic field sensors, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines the self-test circuitry with the normal operational circuitry of the magnetic field sensor, merging multiple functions into a single integrated device. The output driver circuit serves both normal signal output and self-test result transmission, reducing the need for separate dedicated test circuits and minimizing overall device complexity while maintaining reliability improvements
Solution Approach 2:
The output driver circuit is designed to perform multiple functions: it drives the output signal during normal operation and also drives the self-test result signal during testing. This multi-functional approach eliminates the need for separate dedicated test output circuits, achieving reliability enhancement without proportionally increasing device complexity
2Reliability
If self-test operations are performed during manufacturing and use, then reliability is improved, but loss of time occurs
Solution Approach 1:
The patent enables self-test operations to be performed during the manufacturing process before the sensor is deployed. By conducting tests in advance, defective sensors are identified and filtered out during production, ensuring only reliable sensors enter the market. This preliminary testing approach prevents future failures without impacting the operational time of reliable sensors
Solution Approach 2:
The self-test capability can be triggered periodically or on-demand during the sensor's operational life. The system can perform quick diagnostic tests at scheduled intervals or when anomalies are detected, minimizing disruption to normal operation while maintaining reliability through regular monitoring
3Reliability
If signal interruption detection is implemented, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the system monitors the output signal line for interruptions or anomalies. When a signal interruption is detected, the system triggers an error indication or activates diagnostic routines. This feedback-based approach enables reliable interruption detection using existing circuit components, avoiding the need for complex dedicated monitoring hardware
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 the reliability of magnetic field sensors by enabling effective self-diagnosis and fault detection within systems, reducing the risk of defective parts entering the market and improving system performance by identifying and addressing issues promptly.
Implementation Method 1
Magnetic field sensors including a magnetic field sensing element, or transducer, such as a Hall Effect element
Implementation Method 2
Magnetic field sensors including a magnetic field sensing element, or transducer, such as a Hall Effect element or a magnetoresistive element
Data Source
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AI summary
A system includes a magnetic target and a magnetic field sensor. The magnetic field sensor comprises an output node; a circuit to detect a magnetic field produced by the magnetic target; and a processor. The processor may be configured to transmit a signal onto the output node representing the detected magnetic field; detect whether the transmitted signal is interrupted by an external source; and, if the signal is interrupted, initiate a self-test of the apparatus. Corresponding methods and apparatuses are also disclosed.