What Is a Temperature Sensor?
A temperature sensor is a sensor that converts ambient or surface temperature into a measurable electrical signal. It's one of the most common measurement types in electronics.
Types
| Type | Property |
|---|---|
| Thermistor (NTC) | Cheap, narrow range |
| Thermocouple | Very wide range |
| RTD (Pt100) | Very precise, expensive |
| Digital IC | Easy, calibrated |
Analog and Digital
Analog sensors (e.g. the LM35) give a voltage proportional to temperature and are read with an ADC. Digital sensors (e.g. the DS18B20) send the temperature directly as digital data over a bus.
Where Is It Used?
Thermostats, weather stations, processor temperature monitoring, refrigerators and industrial process control.
Accuracy and Resolution
When choosing a sensor two concepts should be distinguished: resolution (the smallest readable difference, e.g. 0.1 °C) and accuracy (closeness to the true value, e.g. ±0.5 °C). In precise applications both are checked from the datasheet.
Common Mistakes
- Choosing the wrong range: trying to measure high temperature with a thermistor.
- Weak thermal contact: if the sensor doesn't contact the surface well, it lags/errs.
- Self-heating: the current through the sensor can heat it and corrupt the reading.
Frequently Asked Questions
Which is the easiest temperature sensor?+
What is used for very high temperature?+
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