Nowadays, the range of temperature detection and control applications is very wide, there are many design options. What is discussed here is in-depth design information and circuits for building thermal detection signal chains using the most popular thermal sensors.

In general, the first step in designing a thermal detection and control system is to determine the temperature range that must be detected and the working environment temperature range. The next step is to select the thermal sensor. There are four types of thermal sensors : silicon, thermal resistor, RTD and thermocouple. Maxim provides a complete signal link scheme or integrated IC, which can receive and process temperature transmitter signals, and provides analog or digital communication channels returned to the control device.

The first step to design the temperature sensor circuit is to select the temperature transmitter to be used. To achieve these purposes, it is necessary to understand the measured medium ( air, water, liquid, solid ) and the measured temperature range. Then we need to know the measurement accuracy that needs to be achieved within the measurement range.

Common temperature transmitters include :

Thermocouple ( range - 180 ° C to + 1300 ° C )

RTD ( range -200 ° C to + 900 ° C )

Thermistor ( range : -50 ° C to + 150 ° C )

Silicon sensor ( range from-20 ° C to + 100 ° C )

While ensuring that the sensor range must meet the application, there are usually additional selection criteria, including the installation of sensors and the cost of signal chains and sensors.

After selecting the transmitter, the next step is to determine how to extract useful signals from the transmitter and transmit them to the controller. The signal extraction circuit is called the signal chain. For each transmitter, there are a variety of signal chains available, including single-chip schemes. Factors that affect the choice of signal chains include accuracy, flexibility, design convenience, and cost