Parallel Sample-and-Hold ADC for Continuous Self-Diagnosis
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Solution Overview
Problem
In in-vehicle systems, the periodic conversion of analog reference voltage for self-diagnosis interrupts the A/D conversion of analog signals from external sensors, potentially reducing the accuracy of motor drive control and limiting the timing of self-diagnosis, which is not preferable for functional safety.
Innovation Solution
An AD converter with a plurality of analog input terminals, a reference signal generating circuit, a sample-and-hold unit with multiple sample-and-hold circuits, and a control unit that allows parallel operation of sampling and holding analog input signals and reference signals, enabling A/D conversion of both without interrupting each other.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the A/D conversion operation of the analog reference voltage is performed periodically for self-diagnosis, then the functional safety is improved, but the A/D conversion operation of the analog signal from the external sensor is interrupted, reducing the accuracy of the drive control
Solution Approach 1:
The sample-and-hold unit is divided into a first sample-and-hold circuit and a second sample-and-hold circuit. The first circuit handles analog input signals from external sensors while the second circuit handles the analog reference voltage for self-diagnosis, allowing simultaneous independent operation of both functions without mutual interference
Solution Approach 2:
The patent transitions from sequential single-channel operation to parallel multi-channel operation by introducing multiple sample-and-hold circuits working simultaneously. This dimensional expansion in operational capacity allows self-diagnosis and external signal conversion to occur in parallel time dimensions
2Measurement precision
If the timing of self-diagnosis using the analog reference voltage is limited to avoid interrupting A/D conversion of external signals, then the accuracy of drive control is maintained, but the execution timing of self-diagnosis is restricted, which is not preferable for functional safety
Solution Approach 1:
The sample-and-hold unit is segmented into multiple independent circuits, each capable of handling different signal types simultaneously. This segmentation removes the need to limit self-diagnosis timing, as the first and second sample-and-hold circuits operate independently without interfering with each other's functionality
3Device complexity
If a single AD converter is used to reduce the size of the microcomputer, then the device complexity is reduced, but the A/D conversion of multiple analog signals must be performed sequentially, causing interruption of conversion operations
Solution Approach 1:
The single AD converter is internally segmented into multiple sample-and-hold circuits that can process different analog signals simultaneously. This internal segmentation enables parallel processing capability within a unified converter structure, maintaining compact size while achieving multi-signal conversion without sequential bottlenecks
Solution Approach 2:
The AD converter is designed with multi-functional sample-and-hold circuits that can handle both external analog signals and internal reference voltage simultaneously. This universal design allows a single device to perform multiple conversion functions in parallel, eliminating the need for separate converters while maintaining high productivity
Data Source
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AI summary
An AD converter includes a plurality of analog input terminals, a reference signal generation circuit that generates an analog reference signal, a sample-and-hold unit that includes a plurality of sample-and-hold circuits sampling the analog reference signal or one of analog input signals from the analog input terminals, a control unit that controls the sample-and-hold unit, and a conversion unit that converts an output signal from the sample-and-hold unit into a digital signal. The control unit controls the sample-and-hold unit to perform the output operation for analog input signal and the sampling operation for the analog reference signal.