When the temperature changes while measuring the resistance of an RTD, the response will be essentially expressed as linear and expressed as resistance. As shown in Figure 1, the resistance curve of the RTD is not completely linear, but has several deviations (showing the straight line used) but can be highly predictable and reproducible. To compensate for this slight nonlinearity, many designers digitize the measured resistance values and apply correction factors using lookup tables within microcontrollers. This reproducibility and stability over a wide temperature range (approximately -250 degree C to+750 degree C) make RTD very useful in sound precision applications, including measuring the temperature of liquids or gases in pipelines and large containers.
The complexity of circuits used to process RTD analog signals varies greatly depending on the application. It is necessary to have components such as amplifiers and analog-to-digital converters (ADCs) that generate unique errors. Only power the sensor when measurement is needed - this method can also achieve low-power operation, but it will make the circuit more complex. Moreover, the output power required for the controller to be plugged in can also increase its internal temperature, thereby jeopardizing the accuracy of precise measurements. A current of only a few mAh, this type of self heating effect will cause temperature deviation (which can be corrected, but must be further considered). Furthermore, please remember that the cost of wire wound platinum RTDs or thin film RTDs may be quite high, especially compared to the cost of integrated circuit sensors.

Thermistor is another type of resistor type controller. There are many types of thermistors, from high-quality and low-priced products to high-precision products. Low cost, low precision thermistors can perform simple and precise measurement or threshold verification functions - this type of varistor requires several components (such as comparators, reference, and discrete varistors), but is very cost-effective and has the resistor temperature characteristics of discrete systems, as shown in Figure 2. If it is necessary to accurately measure a wide range of temperatures, you will need to carry out a lot of linearization solutions. Effectively correcting multiple temperature points will be necessary. In order to achieve higher accuracy, more expensive and smaller tolerance thermistor arrays can be used to help solve this nonlinear problem, but these arrays are usually not as sensitive as individual thermistors.
Due to the increased complexity and cost of multi trip point systems, low-cost thermistors are typically only used for applications with the lowest functional requirements, including toasters, coffee makers, refrigerators, and hair dryers. In addition, thermistors may also face the challenge of self heating (usually at higher temperatures, when their resistors are lower). Like RTD, the root cause of the inability to use thermistors at low power voltages has not been found, but please remember that the lower the full proportional output, the lower the sensitivity of the system directly converted by the characteristics of analog-to-digital converters (ADCs). This low-power application also needs to increase the complexity of the circuit, making it very sensitive to noise errors. Thermistors can operate in the temperature range of -100 degree to+500 degree , although most thermistors have a rated maximum operating temperature range of+100 degree to+1509C

A thermocouple includes a junction of two wires made of different materials. For example, a type thermocouple is composed of iron and constantan. Contact 1 is at the measured temperature, while contact 2 and contact 3 are at different temperatures measured by an LM35 analog temperature sensor. The output voltage is roughly proportional to the difference between these two temperature values.
Due to the very low sensitivity of platinum thermistors (in the heavyweight range of tens of microvolts per Celsius), you will have to use a low offset amplifier to generate usable output operating voltage. Within the working range of thermocouples, the nonlinearity of the temperature voltage transfer function usually requires compensation circuits or lookup tables, just like RTDs and thermocouples. Little did they know that despite this defect, platinum thermistors are still very fashionable, especially in applications such as electric ovens, water and electricity heaters, kilns, testing equipment, and other industrial production solutions - because the thermal quality of platinum thermistors is very low, and the operating temperature range (operating temperature can be extended to around 2300 degree ) is very complex, (temperature sensors)

The IC sensor operates within the temperature range of -55 degree C to+150 degree C. Some|C sensors operate up to+200 degree . There are various integrated IC sensors, and the most common four are integrated IC sensors with analog output devices, digital interface devices, remote temperature sensors, and temperature regulator functions! C sensor (temperature switch). The proposed output components (usually operating voltage output, but some also have backup power flow output) are most likely passive solutions when using ADC to intelligently solve the output data signal. Digital interface devices typically use a dual wire interface (12C or PMBus) with built-in ADC

There are many advantages to using integrated circuit sensors, including: low power consumption; Can provide small packaging products (some sizes as small as {{0}}.8mm x 0.8mm); Low device costs can also be achieved in some applications. Furthermore, as integrated circuit sensors are calibrated during production testing, further calibration is not necessary. They are commonly used in fitness tracking applications, wearable products, computing systems, data recorders, and automotive applications.
Experienced circuit board designers will use the most suitable solution based on the final product requirements. Table 1 shows the relative advantages/labor potential of each temperature sensor. (Pressure sensor)