Non-Ratiometric Sensor Fault Trip Stability
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Solution Overview
Problem
Conventional magnetic field sensors have ratiometric fault trip points that are sensitive to changes in supply voltage, leading to inconsistent performance in noisy or varying environments.
Innovation Solution
A sensor design with a non-ratiometric fault trip point system, where a fixed gain signal path allows users to set a constant fault trip point using external resistors, and a signal processing module converts ratiometric voltage to a fixed output independent of the supply voltage, using an ADC and DAC with a bandgap reference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ratiometric fault trip point is used with a resistor divider network from Vcc, then the trip point voltage moves with Vcc to maintain a constant ratio, but the fault trip level changes as the supply voltage changes, leading to inconsistent sensor sensitivity
Solution Approach 1:
The patent introduces an intermediary voltage reference (Vref) that is independent of the supply voltage Vcc. This reference voltage serves as a mediator between the supply voltage and the fault trip point comparison, allowing the trip point to remain stable regardless of Vcc variations. The resistor divider network now divides Vref instead of Vcc, creating a stable reference level for fault detection that does not ripple with supply voltage changes.
Solution Approach 2:
The patent changes the reference parameter from which the fault trip point is derived. Instead of using the supply voltage Vcc as the reference (ratiometric approach), the system uses an independent stable voltage reference Vref. This parameter change decouples the fault trip point from supply voltage variations, maintaining consistent sensor sensitivity across different operating conditions.
2Reliability
If regulated voltages are used in noisy and/or extreme environments, then voltage regulation is provided, but the regulated voltages can still vary, impacting fault trip point accuracy
Solution Approach 1:
The patent introduces an intermediary voltage reference (Vref) that is independent of the supply voltage Vcc. This reference voltage serves as a mediator between the supply voltage and the fault trip point comparison, allowing the trip point to remain stable regardless of Vcc variations. The resistor divider network now divides Vref instead of Vcc, creating a stable reference level for fault detection that does not ripple with supply voltage changes.
Solution Approach 2:
The patent changes the reference parameter from which the fault trip point is derived. Instead of using the supply voltage Vcc as the reference (ratiometric approach), the system uses an independent stable voltage reference Vref. This parameter change decouples the fault trip point from supply voltage variations, maintaining consistent sensor sensitivity across different operating conditions.
3Adaptability or versatility
If a fixed gain signal path is used, then constant sensor sensitivity is achieved, but the fault trip point must be set independently of the supply voltage, requiring additional circuit complexity
Solution Approach 1:
The patent introduces an intermediary voltage reference (Vref) that is independent of the supply voltage Vcc. This reference voltage serves as a mediator between the supply voltage and the fault trip point comparison, allowing the trip point to remain stable regardless of Vcc variations. The resistor divider network now divides Vref instead of Vcc, creating a stable reference level for fault detection that does not ripple with supply voltage changes.
Data Source
AI summary
Methods and apparatus for a sensor having non-ratiometric fault trip level setting. In embodiments, a sensor has a sensing element with a fixed gain. A signal processing module receives the fault trip level setting and maintains the fault trip level setting constant during changes in the supply voltage.