Tri-State Detection Circuit Using Unidirectional Conduction
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Solution Overview
Problem
Conventional state detection circuits are limited in their ability to determine the state of an input node, as they can only detect whether a pin is floating or connected to ground potential, and are inefficient in terms of quiescent current and area size, with limitations to low-voltage applications.
Innovation Solution
A state detection circuit comprising a unidirectional device circuit and a determination circuit that applies a test voltage to an input node, allowing for the detection of whether the node is floating, electrically connected to ground potential, or externally connected to voltage, with a discharge circuit for voltage discharge and a clamping device to prevent voltage exceeding maximum ratings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional state detection circuits are used to determine the state of an input node, then the detection can identify whether the pin is floating or connected to ground potential, but the circuit cannot determine external voltage connections and is limited to low-voltage applications
Solution Approach 1:
The detection process is divided into distinct stages: a discharge stage that prepares the input node by discharging any existing voltage, and a detection stage that applies test voltage and measures the response. This segmentation allows the same circuit to handle multiple detection scenarios (floating, ground, external voltage) systematically without requiring separate circuits for each case.
Solution Approach 2:
Before the actual detection occurs, a discharge stage is performed to clear any residual voltage from the input node. This preliminary action ensures that the detection stage starts with a known state, enabling accurate determination of whether the node is floating, grounded, or connected to external voltage, thereby expanding detection versatility without increasing complexity.
2Measurement precision
If conventional state detection circuits are used, then the circuit can detect floating or ground states, but it occupies large area and consumes high quiescent current
Solution Approach 1:
The circuit merges multiple detection functions into a single integrated structure. The same detection circuitry is used to identify all three states (floating, ground, external voltage) by varying the test voltage and observing the response, rather than using separate circuits for each detection type. This merging reduces the overall circuit area while maintaining detection precision.
Solution Approach 2:
The detection circuit is designed with multi-functionality to handle three different detection scenarios (floating, ground connection, external voltage connection) using a single circuit configuration. By universally applying test voltages and analyzing the current response, the circuit achieves accurate state detection without requiring multiple specialized circuits, thereby reducing area occupancy.
3Adaptability or versatility
If conventional state detection circuits are used, then the circuit can detect two states (grounded or floating), but it cannot detect external voltage connections
Solution Approach 1:
The circuit employs periodic action by alternately applying different test voltages (first test voltage and second test voltage with different polarities or magnitudes) to the input node and measuring the current response at different time intervals. This periodic testing enables the circuit to distinguish between floating, ground, and external voltage states based on the characteristic current responses, expanding detection range while maintaining low quiescent current during non-detection periods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables tri-state detection with reduced area occupancy and applicability to both high and low voltage environments, improving efficiency and accuracy in determining the state of input nodes.
Implementation Method 1
a unidirectional device circuit, configured to unidirectionally conduct a test node to a detection node
Data Source
AI summary
A state detection circuit for detecting whether a state of an input node is floating, grounded, or electrically connected to an external voltage includes: a unidirectional device circuit and a determination circuit. The unidirectional device circuit electrically conducts a test node to a detection node unidirectionally. The detection node is coupled to the input node. The test node, the unidirectional device circuit, the detection node and the input node form a current path. The determination circuit determines a state of the input node according to a voltage level of the detection node. Within a detection stage, the state detection circuit provides a test voltage at the test node. A voltage of the detection node is determined by the input node, the test voltage, and a characteristic of the unidirectional device circuit.