AC/DC Voltage Detection Circuit Using Rising-Edge Flip Counting
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Solution Overview
Problem
Integrated circuits (ICs) require a circuit to accurately detect whether an input signal is alternating current (AC) or direct current (DC) while maintaining balance between complexity, detection speed, and cost, with existing solutions failing to achieve optimal performance and cost efficiency.
Innovation Solution
The AC/DC voltage detection circuit includes a rising edge trigger circuit and a detection and output circuit, which samples the operating voltage with a preset clock period, using a bias voltage to differentiate between AC and DC signals by detecting target flips in the comparator output, thereby determining the AC/DC characteristic of the input signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a specially designed circuit is used to detect AC/DC voltage characteristics, then detection accuracy is improved, but circuit complexity increases
Solution Approach 1:
The detection circuit is divided into two functional modules: a rising edge trigger circuit that samples voltage changes and generates trigger signals, and a detection and output circuit that counts trigger signals to determine AC/DC characteristics. This segmentation allows each module to perform a specific function with simple structure, achieving high detection accuracy without excessive complexity.
Solution Approach 2:
The rising edge trigger circuit samples the operating voltage periodically at the rising edge of clock signals. By using periodic sampling at fixed time intervals, the circuit can accurately detect voltage changes characteristic of AC signals while maintaining a simple periodic operation mode rather than requiring complex continuous monitoring.
2Productivity
If sampling frequency is increased to improve detection speed, then detection speed is improved, but circuit complexity and power consumption increase
Solution Approach 1:
The circuit uses periodic sampling at the rising edge of clock signals with a predetermined clock period. This approach achieves fast detection by utilizing the natural periodicity of AC signals (50/60Hz) and sampling only at critical moments (rising edges), rather than requiring high-frequency continuous sampling that would increase complexity and power consumption.
Solution Approach 2:
The circuit pre-configures the clock period to match the expected AC signal frequency characteristics. By preparing the sampling timing in advance based on known AC signal properties, the circuit can quickly detect AC/DC characteristics without requiring complex real-time frequency analysis or adaptive sampling rate adjustment.
3Measurement precision
If more sampling points are used to improve detection accuracy, then detection accuracy is improved, but circuit complexity increases
Solution Approach 1:
Instead of using multiple complex voltage dividers or sampling networks, the patent segments the detection function into trigger generation and trigger counting. The trigger circuit generates discrete trigger signals at voltage change points, and the detection circuit counts these triggers over a predetermined period. This segmentation achieves high accuracy by capturing all voltage changes without requiring multiple simultaneous sampling points.
Solution Approach 2:
The patent replaces what would traditionally require multiple physical voltage sampling points and complex analog signal processing with a digital counting approach. By substituting mechanical/analog multiple-point sampling with digital trigger signal counting, the circuit achieves high detection accuracy with simpler digital logic rather than complex analog circuitry.
Data Source
AI summary
The present disclosure provides an alternating current (AC)/direct current (DC) voltage detection circuit, which includes a rising edge trigger circuit and a detection and output circuit connected to an output terminal of the rising edge trigger circuit. When an increase of the operating voltage at the rising edge of the operating voltage in one clock period is greater than the magnitude of a preset bias voltage, an output signal of the output terminal undergoes at least one target flip between a high level and a low level. When a detection result shows that the output signal of the rising edge trigger circuit undergoes preset m (a natural number) target flips in preset M consecutive clock periods, the detection and output circuit generates an AC determination signal.