AD Converter Self-Check Circuit for Multi-Channel Reliability
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Solution Overview
Problem
Conventional microcomputers with a single built-in AD converter struggle to accurately perform AD conversion across multiple analog input terminals, leading to system performance issues and inadequate reliability checks, particularly in applications like automotive control systems.
Innovation Solution
An AD converter with an input circuit, operation circuit, and bus interface is designed, featuring a pull-down circuit, reference voltage conversion result storing register, and checking register to ensure proper operation and accuracy of AD conversion across multiple channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single AD converter is used for multiple analog input terminals, then device complexity is reduced, but reliability of AD conversion cannot be ensured
Solution Approach 1:
The patent implements a self-diagnosis function that performs preliminary checks on the AD converter's internal circuits and signal transmission paths before actual conversion operations. This includes testing the sample-hold circuit, comparator, and data output circuits to ensure they are functioning properly, thereby maintaining reliability without requiring multiple converters
Solution Approach 2:
The patent incorporates a feedback mechanism where the AD converter monitors its own operation status and converts the diagnosis results into digital signals that can be read by the CPU. This feedback loop enables continuous verification of conversion accuracy and system reliability, allowing the single converter to maintain high reliability through self-monitoring
2Measurement precision
If external check circuits are added to verify AD conversion accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the self-diagnosis function directly into the AD converter's internal structure, combining the conversion function and diagnosis function into a single integrated unit. The same converter circuits perform both normal conversion and self-check operations, eliminating the need for separate external verification circuits and maintaining measurement precision while reducing overall device complexity
Solution Approach 2:
The AD converter performs self-diagnosis by automatically testing its own internal circuits and monitoring its operation status without requiring external test equipment. The converter uses its existing resources (power supply, signal paths, processing circuits) to verify its own accuracy, achieving high measurement precision through self-service rather than external intervention
Data Source
AI summary
An AD converter includes an input circuit, an operation circuit and a bus interface. The input circuit is provided with a pull-down circuit, which is capable of pulling down an analog signal input side of a sample-hold circuit whether an analog signal is inputted or not. The operation circuit is provided with a reference voltage conversion result storing register, which is capable of storing a conversion result of an analog reference voltage inputted periodically separately from a conversion result of the analog signal inputted through the sample-hold circuit. The operation circuit is further provided with a check register, which is capable of writing in and reading out data for checking operation of a signal transfer system including a bus interface through the bus interface. Thus, it is made possible to confirm normality of an external part and an internal part of the AD converter.