Sensor OBD Circuit Error Detection via ADC Readback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional sensor systems face limitations in detecting both internal and external errors due to reduced signal levels and dependence on digital-to-analog converters (DAC) and output drivers, which can lead to incomplete diagnostic coverage and increased complexity.
Innovation Solution
The implementation of on-board-diagnostic (OBD) circuits with charge pumps and switches, independent of DAC and output drivers, allows for error detection by analyzing readback signals via an ADC multiplexer and control circuitry, enabling diagnostic outputs indicative of errors without affecting the original signal range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional OBD circuits are implemented to detect external line interruptions, then external error detection capability is improved, but the operating range of the analog output is reduced due to clamping ranges
Solution Approach 1:
The patent segments the error detection function into two independent parts: external error detection via OBD circuits and internal error detection via readback comparison. This allows each function to operate independently without interfering with the other, preserving the full analog output range while maintaining both detection capabilities.
Solution Approach 2:
The patent introduces an intermediary readback path that copies the analog output signal through a separate ADC and comparison circuit. This intermediary path enables internal error detection without affecting the main output signal, allowing full utilization of the analog output range.
2Reliability
If expanded diagnostic output values or clamping ranges are defined to fulfill safety requirements, then internal functionality diagnostics are improved, but the output signal level is further reduced
Solution Approach 1:
The patent segments the diagnostic function into an independent readback path that does not share the output driver stage. The readback ADC and comparison circuit operate separately, allowing full diagnostic coverage without imposing clamping ranges on the main output signal.
Solution Approach 2:
The patent creates a copy of the analog output signal through the readback path, which is then analyzed by the ADC and comparison circuit. This copying mechanism enables internal error detection without affecting the original output signal level or range.
3Reliability
If additional components are added to provide diagnostic capabilities for all IC components, then diagnostic coverage is improved, but the size, cost, and complexity of the circuit increase
Solution Approach 1:
The patent makes the readback ADC and comparison circuit serve multiple functions: they detect internal errors in the DAC, output driver, and sensor interface, and also enable external error detection when combined with the OBD circuits. This multi-functionality achieves comprehensive diagnostic coverage without requiring separate dedicated circuits for each component.
Solution Approach 2:
The patent merges the internal and external error detection functions into a unified diagnostic system. The readback comparison circuit works in conjunction with the OBD circuits to provide comprehensive error detection, reducing the need for separate independent diagnostic systems.
Data Source
AI summary
Integrated circuit systems, such as sensor systems, having on-board-diagnostic (OBD) circuits for the detection of errors presenting internal to the systems are disclosed, along with related methods. In one embodiment, an ADC multiplexer receives analog output readback from an output driver and provides a signal triggering an OBD circuit for internal error indication performed completely independent of digital-to-analog converters (DAC) and output drivers, which can be the point of failure.