SAR ADC Input Range Detection for Early Overvoltage Protection
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Solution Overview
Problem
Conventional analogue-to-digital converter (ADC) circuitry faces challenges in detecting overvoltage efficiently, as existing methods require additional circuitry and result in high delays, increasing the risk of damage to the ADC circuitry and saturation in digital output.
Innovation Solution
The ADC circuitry employs successive-approximation control circuitry to determine if the analogue input voltage signal is outside the full-scale range by analyzing comparison results from successive approximation operations, allowing for early detection of overvoltage without the need for additional circuitry and enabling protection mechanisms like attenuation or isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional overvoltage detection methods are used, then overvoltage can be detected, but additional circuitry is required and detection delay is high
Solution Approach 1:
The voltage comparator is made multi-functional by using it for both the standard successive approximation operations and for overvoltage detection. The comparator's existing functionality is extended to simultaneously perform overvoltage detection by monitoring comparison results during normal conversion operations, eliminating the need for separate dedicated overvoltage detection circuitry.
Solution Approach 2:
The ADC circuitry performs its own overvoltage detection using its existing components without requiring external or additional detection circuits. The successive approximation control circuitry analyzes comparison results from the voltage comparator to determine if an overvoltage condition exists, allowing the system to self-monitor and self-protect.
2Reliability
If conventional overvoltage detection methods are used, then overvoltage can be detected, but detection delay is high causing damage risk
Solution Approach 1:
Overvoltage detection is performed preliminarily during the successive approximation operations before the complete conversion process finishes. By analyzing comparison results from intermediate approximation operations, the system can detect overvoltage conditions earlier than waiting for final conversion completion, reducing detection delay and enabling faster protective action.
Solution Approach 2:
The successive approximation control circuitry continuously monitors feedback from the voltage comparator's comparison results during each approximation operation. This real-time feedback mechanism allows immediate detection of overvoltage conditions as they occur during the conversion process, rather than waiting for a separate detection phase.
3Measurement precision
If additional circuitry is added for overvoltage detection, then detection accuracy improves, but device complexity increases
Solution Approach 1:
The voltage comparator serves dual purposes: performing standard successive approximation comparisons and simultaneously providing overvoltage detection through its comparison results. This multi-functional approach maintains detection accuracy while avoiding the complexity of adding separate dedicated overvoltage detection circuitry.
Solution Approach 2:
The existing ADC components, particularly the voltage comparator and successive approximation control circuitry, are utilized to perform overvoltage detection without requiring additional specialized circuitry. The system leverages its own operational data to achieve accurate overvoltage detection.
Data Source
AI summary
Analogue-to-digital converter, ADC, circuitry, including: an analogue input terminal; a comparator having first and second comparator-input terminals; and successive-approximation control circuitry to apply a potential difference across the first and second comparator-input terminals based on an input voltage signal, and to control the potential difference for a series of successive approximation operations to cause the comparator to test in each successive approximation operation whether a magnitude of an analogue input voltage signal is larger or smaller than a corresponding test value, the test value for each successive approximation operation being, dependent on a comparison result generated by the comparator in the preceding approximation operation, bigger or smaller than the test value for the preceding approximation operation by a difference amount configured for that successive approximation operation.