Thermistor A/D Resolution Switching for Wide-Range Temperature Sensing
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Solution Overview
Problem
Existing temperature measurement systems using NTC thermistors face reduced accuracy in wide temperature ranges due to saturated temperature dependence, leading to long A/D conversion times with high-resolution converters, which can result in incorrect data acquisition.
Innovation Solution
A semiconductor device with a series resistor selection circuit that controls the A/D converter to operate in low bit count mode during resistor selection and high bit count mode after optimal resistor determination, ensuring accurate temperature measurement within a predetermined voltage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution A/D converter is used for accurate temperature measurement, then measurement precision is improved, but conversion time increases
Solution Approach 1:
The A/D converter operates in two different resolution modes (low bit count mode during resistor selection, high bit count mode after selection) to dynamically adapt to different operational requirements, achieving both speed and accuracy at appropriate times
Solution Approach 2:
The system performs preliminary temperature measurement using low-resolution A/D conversion during the resistor selection phase, then switches to high-resolution conversion only after optimal resistor selection, avoiding unnecessary high-resolution conversion throughout the entire process
2Adaptability or versatility
If series resistor is selected to extend temperature measurement range, then adaptability is improved, but temperature measurement accuracy decreases due to saturated temperature dependence
Solution Approach 1:
The system dynamically selects from multiple series resistors with different resistance values to optimize the divided voltage output for different temperature ranges, preventing saturation and maintaining measurement accuracy across extended temperature ranges
Solution Approach 2:
The system changes the resistance value parameter of the series resistor to optimize the voltage division ratio, ensuring the divided voltage remains within the optimal range for the A/D converter across varying temperature conditions
3Productivity
If low bit count mode is used during resistor selection, then conversion speed is improved, but measurement precision decreases
Solution Approach 1:
The system performs preliminary resistor selection using low-resolution A/D conversion, then switches to high-resolution conversion only after selection is complete, achieving fast selection without sacrificing final measurement accuracy
Solution Approach 2:
The A/D converter resolution is dynamically adjusted based on the operational phase: low resolution during resistor selection for speed, high resolution after selection for accuracy
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
This approach reduces the time required to select an optimal series resistor and improves measurement accuracy by utilizing high bit count mode only after resistor selection, thereby enhancing temperature data acquisition efficiency.
Implementation Method 1
a thermistor for temperature detection
Implementation Method 2
a divided voltage obtained by dividing an internal power supply voltage between the thermistor and the selected series resistor
Data Source
AI summary
A semiconductor device, including: a thermistor for temperature detection; a series resistor selection circuit including a series resistor group connected in series with the thermistor, the series resistor selection circuit being configured to select a series resistor from the series resistor group according to a selection signal; an analog/digital (A/D) converter that performs A/D conversion on a divided voltage obtained by dividing an internal power supply voltage between the thermistor and the selected series resistor to generate divided voltage data, and outputs the divided voltage data; and a control circuit. The control circuit, during a period of selecting the series resistor, controls the A/D converter to operate in a low bit count mode, such that the selected series resistor causes the divided voltage data to fall within a predetermined voltage range, and controls the A/D converter to operate in a high bit count mode after selecting the series resistor.