Auto-ranging Thermistor Temperature Detection Circuit
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Solution Overview
Problem
Existing thermistor-based temperature detection systems face accuracy issues due to the static nature of constant current/voltage sources, leading to reduced temperature detection precision, especially at extreme temperatures, resulting in potential over- or under-heating and damage to systems.
Innovation Solution
An auto-ranging thermistor temperature detection circuit that employs adjustable power sources and auto-range hysteresis logic to dynamically adjust current or voltage supplied to the thermistor based on sensed voltage thresholds, improving measurement accuracy across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant current source or constant voltage source is used to detect thermistor resistance variation, then the circuit structure is simple, but the temperature detection accuracy is reduced at extreme temperatures
Solution Approach 1:
The patent applies the dynamics principle by transitioning from static constant current/voltage sources to a dynamic power supply system. The auto-range hysteresis logic continuously monitors thermistor voltage and dynamically adjusts the current or voltage supplied to the thermistor based on temperature ranges, enabling the circuit to adapt its operating parameters in real-time to maintain optimal detection accuracy across extreme temperatures.
Solution Approach 2:
The patent implements parameter changes by modifying the electrical parameters (current or voltage) supplied to the thermistor based on temperature conditions. The auto-range hysteresis logic changes the power supply parameters dynamically, adjusting the amplitude of current or voltage to match different temperature ranges, thereby resolving the accuracy issue at extreme temperatures while managing circuit complexity.
2Measurement precision
If the power supply voltage or current is increased to improve detection accuracy, then measurement precision improves, but power consumption increases
Solution Approach 1:
The system dynamically adjusts power consumption by continuously monitoring thermistor voltage and automatically switching between different power supply modes (first level and second level). This dynamic adaptation ensures high measurement precision is maintained only when necessary, while reducing power consumption during normal operating conditions.
Solution Approach 2:
The patent changes power supply parameters (voltage or current level) based on temperature detection needs. The auto-range hysteresis logic switches between a first power level for normal operation and a second power level for enhanced accuracy, thereby optimizing the balance between measurement precision and power consumption according to actual environmental conditions.
3Measurement precision
If an auto-ranging system with adjustable power sources is implemented, then temperature detection accuracy is improved, but device complexity increases
Solution Approach 1:
The auto-range hysteresis logic operates autonomously to monitor thermistor voltage and automatically adjust power supply levels without external intervention. This self-service mechanism manages the increased device complexity by automating the adaptation process, allowing the system to maintain high temperature detection accuracy while minimizing the need for external control mechanisms.
Solution Approach 2:
The system implements feedback through the auto-range hysteresis logic, which continuously monitors the thermistor voltage and uses this information to automatically adjust the power supply output. This feedback loop manages device complexity by creating a self-regulating system that adapts to temperature changes, maintaining detection accuracy without requiring complex external control systems.
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 solution enhances temperature measurement accuracy and reduces power consumption by dynamically adjusting current or voltage, preventing over- or under-heating and improving the reliability of thermistor-based temperature detection systems.
Implementation Method 1
The resistance of a PTC-type thermistor increases as its temperature increases; and the resistance of an NTC-type thermistor decreases as its temperature increases.
Data Source
AI summary
An apparatus for detecting temperature includes an adjustable current source operable for supplying a current, a thermistor coupled to said adjustable current source, and an auto-range hysteresis logic coupled to said thermistor and said adjustable current source operable for outputting a signal to control said adjustable current source by sensing a voltage across said thermistor. A method for detecting temperature is also disclosed.