How To Design Accurate ‘Temperature Monitoring Systems’?

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Modern electronic systems often use sensors for temperature monitoring and to provide protection from excessive temperature excursions. This can encompass varied applications and environments ranging from an electronic chip in a laptop or other portable electronic equipment, a part of an automobile engine, ambient air temperature, temperature of a weld in a laser welding application, or temperature of bearings or shafts in machines. To handle these diverse demands, a large number of sensors and devices are available to designers including thermistors, thermocouples, RTDs, and temperature-sensor ICs.

Here, we’ve put together some ready-to-use temperature sensing reference designs from leading industry players which could be used to solve any temperature measurement problem whatever be the demands of your application in terms of cost, accuracy, efficiency, safety, repeatability, and many more factors.

• Temperature Measurement with 0.25 ° C Accuracy with 3 Input Channels: Analog Devices provides a reference design ideal for process control and industrial automation applications where a cost-effective, accurate temperature measurement is required over the wide temperature ranges of -200 °C to +1200 °C offered by thermocouples. The design can simultaneously measure temperature from three thermocouples using a high-precision ADC. More on this Reference Design
• Temperature Sensor for Fitness Trackers: Here is a reference design from TI which features a small USB form factor and leverages an IC temperature sensor LMT70 whose accuracy is as good as 0.13 °C at human body temperatures, making it ideal for use in medical and wearable applications such as body monitors or fitness watches. More on this Reference Design
• Temperature Sensor for Food/Chemical Processing & Textile Industries: Maxim Intergrated’s industrial form factor design targets food processing, chemical processing, textile production, and air, gas, and liquid temperature measurements. Apart from offering benefits such as wide temperature ranges and high accuracies with 2, 3 or 4-wire Platimum RTDs (PT100), the design consumes minimal power by utilizing an industrial DC-DC step-down converter. Finally, the design utilises widely supported IO-Link communication to enhance configurability and control. Using IO-link communication, the board can be connected to a USB IO-link master for analysis on a PC. More on this Reference Design
• Low-cost, Flexible Temperature Sensor Module For PLCs: This low-cost and flexible temperature sensor module from TI can interface with both thermocouples and RTDs for industrial temperature measurement in a range of applications like PLCs, factory automation, process control, portable instrumentation, data acquisition systems and industrial robotics. Other benefits to using the design include saving on board space, and reduced design efforts, time to market, and cost. More on this Reference Design
• Temperature Sensing Design For PLCs Measures Over -200 °C to +400 °C: Specially designed for PLCs, field Instruments and distributed control systems, this reference design from Analog devices measures temperature over -200 °C to +400 °C using a T-type thermocouple. More on this Reference Design
• Temperature Sensing System With ±0.05°C Resolution: If your application requires good resolutions, another measurement system from Microchip provides a ±0.05°C resolution using a K-type Thermocouple over the entire thermocouple range. A GUI for temperature data log is also included to plot the temperature data on a PC using a USB interface. Overall accuracy is improved by improving thermocouple accuracy using a silicon temperature sensor of 0.0625°C resolution over -40°C to +125°C. More on this Reference Design
• Over-Temperature Protection Circuit by MCU and NTC Thermistor: This design uses an integrated thermistor for temperature sensing of power chips in a smart power module which provides efficient motor control in air conditioners. Most customers want to know the temperature of power chips such as IGBTs operated in high-voltage conditions precisely due to the impact on quality, reliability, and lifetime improvement. This thermistor is located in ceramic substrate with the power chip (IGBT/FRD). Therefore, the thermistor can accurately reflect the temperature of the power chip. More on this Reference Design. For details of the temperature-sensing circuit, click here.
• Temperature Measurement With ±1°C Accuracies Using Thermocouples: Here is a reference design from Maxim Integrated which can measure temperature with a thermocouple and platinum resistance temperature detector (PRTD) for many industrial and medical applications using a high-resolution ADC. The design is cost effective, compact, and low power. No additional components are needed for precise temperature measurement. The design also describes a system and software which can be used to achieve accuracies of ±1°C. More on this Reference Design