Current Detection Circuit Hysteresis for Noise-Stable Output Sensing
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Solution Overview
Problem
Existing current detection circuits in power supply semiconductor integrated circuits lack effective hysteresis mechanisms, leading to malfunctions due to noise when detecting open or short states of output terminals.
Innovation Solution
A current detection circuit is designed with a hysteresis circuit that includes a current source circuit and a switch, which adjusts the current flowing through a current-to-voltage converter to provide hysteresis to the comparator's comparison operation, preventing operation in the saturation region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a comparator is used to detect current by comparing voltage with a threshold, then detection function is achieved, but noise causes repeated output changes near threshold value
Solution Approach 1:
The patent applies feedback by using the comparator output to control a switch that feeds back to the current-to-voltage converter input. When the comparator detects that the converted voltage exceeds the threshold, it activates the switch to discharge the capacitor, creating a feedback mechanism that prevents continuous output changes and stabilizes the detection system against noise.
Solution Approach 2:
The patent implements beforehand cushioning by using a capacitor to accumulate charge and a switch to discharge it when needed. This creates a buffer that cushions against noise-induced fluctuations near the threshold value, preventing the comparator output from repeatedly changing due to small voltage variations caused by noise.
2Reliability
If hysteresis is provided to prevent noise-induced malfunctions, then output stability is improved, but transistor may operate in saturation region
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the resistance value in the current-to-voltage converter through the switch mechanism. When the switch is activated, it changes the effective resistance by providing an alternative discharge path for the capacitor, thereby changing the conversion parameter to provide hysteresis while maintaining the transistor in the active region and preventing saturation.
3Object-affected harmful factors
If a switch is added to provide hysteresis by controlling current flow, then noise immunity is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the switch to serve multiple functions: it acts as a hysteresis control element, a current control switch, and a protection mechanism against saturation. This multi-functional design reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving improved noise immunity through hysteresis.
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
The proposed solution effectively provides hysteresis to the comparison operation of the comparator, enhancing noise immunity and preventing malfunctions due to noise, while ensuring that the transistors in the hysteresis circuit do not operate in the saturation region.
Implementation Method 1
a current-to-voltage converter that converts a current to be detected or a reference current into a voltage
Implementation Method 2
a hysteresis circuit for providing hysteresis to a comparison operation of the comparator
Data Source
AI summary
Disclosed is a current detection circuit including: a current-to-voltage converter; a comparator including one input terminal to which a voltage that is current-to-voltage converted is input and the other input terminal to which a voltage as a reference for comparison or a voltage converted from the current to be detected is input; and a hysteresis circuit. The hysteresis circuit includes: a current source circuit; and a switch connected in series with the current source circuit, and the switch is switched to an on state or an off state by output of the comparator, thereby a current flowed in the current-to-voltage converter is increased or decreased by the current of the current source circuit, and the voltage converted from the current to be detected or from the reference current changes and thereby the hysteresis circuit provides hysteresis to the comparison operation of the comparator.