Magnetic Field Sensor Self-Test via Time-Multiplexed Diagnostics

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Solution Overview

Problem

Magnetic field sensors require external diagnostic functions to perform diagnostics, which disrupt their primary function and are not continuously available for sensing external magnetic fields.

Innovation Solution

The implementation of internal self-test diagnostics using a time-multiplexed signal that alternates between magnetic and diagnostic signals, allowing for continuous operation and fault detection without external intervention, utilizing a magnetic sensing element, sensor biasing current source, switching network, and fault monitoring module.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If external diagnostic functions are used to perform diagnostics, then fault detection capability is improved, but the sensor must stop its primary sensing function and requires external control

Engineering Contradiction:

Improvefault detection capabilityVSAvoidcontinuous sensing operation

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The magnetic field sensor performs self-diagnostic testing using internal diagnostic components without requiring external diagnostic functions. The sensor autonomously generates diagnostic signals, switches between sensing and diagnostic modes, and monitors its own operational status, thereby eliminating the need for external control while maintaining continuous sensing operation.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The sensor implements periodic switching between primary sensing functions and self-diagnostic testing through a switching network. The magnetic sensing element alternates between generating magnetic signals during sensing periods and diagnostic signals during diagnostic periods, enabling both functions to occur sequentially without external intervention.

Inventive Principle:

Principle #19Periodic action

2Reliability

If the sensor stops primary function to perform diagnostics, then diagnostic accuracy is improved, but operational continuity deteriorates

Engineering Contradiction:

Improvediagnostic accuracyVSAvoidsensing operation interruption

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The sensor maintains continuous useful action by rapidly alternating between sensing and diagnostic modes. The switching network enables the magnetic sensing element to continuously perform its primary sensing function while periodically inserting self-diagnostic tests, ensuring that sensing operation is interrupted only momentarily while diagnostic accuracy is maintained through dedicated diagnostic signal periods.

Inventive Principle:

Principle #20Continuity of useful action

3Extent of automation

If internal self-test diagnostics are implemented, then operational autonomy is improved, but device complexity increases

Engineering Contradiction:

Improveautonomous diagnostic capabilityVSAvoidinternal circuit structure

Core Design Contradiction:

Extent of automationVSDevice complexity

Solution Approach 1:

The magnetic sensing element serves multiple functions by acting as both the primary sensor for detecting external magnetic fields and the diagnostic element for self-testing. The same element generates both magnetic signals during sensing periods and diagnostic signals during diagnostic periods, eliminating the need for separate diagnostic hardware and reducing overall device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The switching network merges the sensing and diagnostic signal paths into a single integrated circuit structure. By combining the biasing current source, switching network, and signal processing components into one unified system, the patent achieves autonomous diagnostic capability without proportionally increasing device complexity.

Inventive Principle:

Principle #5Merging (Combining)

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 continuous magnetic field sensing while performing self-diagnostic testing in the background, ensuring the magnetic field sensor can detect faults and recover without stopping its primary function.

Implementation Method 1

Hall effect elements generate an output voltage proportional to a magnetic field

Methodology Applied

Scientific EffectMagnetic field sensing: Hall Effect

Implementation Method 2

magnetoresistance elements change resistance in proportion to a magnetic field

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Data Source

PatentUS10527703B2Circuits and techniques for performing self-test diagnostics in a magnetic field sensor

Publication Date: 2020.01.07 ALLEGRO MICROSYSTEMS LLC

AI summary

Systems and methods are provided herein for performing a self-test of a magnetic field sensor using internal diagnostic components for fault detection. The magnetic field sensor includes a magnetic sensing element coupled to a sensor biasing current source and a switching network coupled to the magnetic sensing element. The switching network includes one or more diagnostics switches and one or more signal switches, and the one or more diagnostic switches are coupled to a diagnostic input current source. The switching network is configured to generate a time-multiplexed signal having a magnetic signal responsive to an external magnetic field in a magnetic signal time period and a diagnostic signal in a diagnostic signal time period. The diagnostic signal may be operable to produce an intermediate signal to have a predetermined sequence between a first state and a second state.