CVH Sensor Self-Testing via Internal Mode Switching
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Solution Overview
Problem
Conventional self-test methods for circular vertical Hall (CVH) sensing elements and magnetic field sensors that rely on external magnetic fields are impractical due to difficulty in controlling the direction and strength of external magnetic fields, limiting their effectiveness during manufacturing and in-field use.
Innovation Solution
A magnetic field sensor with a switching network and self-test processor that allows for self-testing without relying on an external magnetic field, by switching between normal and self-test modes to simulate magnetic field conditions, using resistance-based voltages to assess the performance of CVH sensing elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external magnetic fields are used for self-testing, then sensor performance can be evaluated, but the direction and strength of external magnetic fields are difficult to control
Solution Approach 1:
The sensor system performs self-testing using its own internal components (switching network and existing sensing elements) rather than requiring external test equipment. The control circuit switches between normal sensing mode and self-test mode, enabling the system to evaluate its own performance without external magnetic fields or additional hardware.
2Reliability
If conventional self-test methods using external magnetic fields are used, then sensor functionality can be verified, but manufacturing costs increase and field reliability improves only marginally
Solution Approach 1:
The switching network and control circuit enable the sensor to perform multiple functions: normal magnetic field sensing operation and self-testing operation. The same hardware infrastructure is used for both sensing and self-diagnosis, eliminating the need for separate test equipment and reducing manufacturing complexity.
Solution Approach 2:
The sensor system performs self-testing using its own internal components (switching network and existing sensing elements) rather than requiring external test equipment. The control circuit switches between normal sensing mode and self-test mode, enabling the system to evaluate its own performance without external magnetic fields or additional hardware.
3Measurement precision
If all output signals from vertical Hall elements are used to determine magnetic field direction, then accurate magnetic field detection is achieved, but the complexity of the sensing element increases
Solution Approach 1:
The CVH sensing element is divided into multiple vertical Hall elements arranged in a circular pattern, with each element contributing to the overall magnetic field detection. The switching network selectively activates and tests individual elements or groups of elements, allowing comprehensive testing without requiring all elements to operate simultaneously, thus managing complexity.
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 reliable self-testing of CVH sensing elements and magnetic field sensors, reducing manufacturing costs and improving field reliability by eliminating the need for controlled external magnetic fields, while effectively identifying sensor performance issues.
Implementation Method 1
A magnetic field sensor can include one or more magnetic field sensing elements... One type of current sensor uses a Hall effect magnetic field sensing element in proximity to a current-carrying conductor.
Implementation Method 2
a switching network operable to switch between a normal mode and a self-test mode... When in the normal mode, the at least one vertical Hall element provides a respective normal mode voltage... When in the self-test mode, the at least one vertical Hall element provides a respective self-test voltage
Implementation Method 3
the self-test voltage is related to a resistance between vertical Hall element contacts of the at least one vertical Hall element, respectively
Data Source
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AI summary
A switching arrangement around a circular vertical Hall (CVH) sensing element can provide a normal mode configuration responsive to magnetic fields at some times, and at least one of a first and a second self-test mode configuration not responsive to a magnetic field but simulating a magnetic field at other times. A corresponding method is also described.