Digital Temperature Sensing Circuit
Created: Mar 25, 2015
No description available.
Temperature sensing equipment is a very useful device for industries like HVAC, medical equipment, automotive, food processing, chemical handling and safety applications. Temperature sensors are used to measure heat in processes to ensure that the operation is in a safe range.
In the design, the circuit uses a digital temperature sensor, specifically, the DS18B20. It is a high temperature with waterproof features. With this sensor, it becomes convenient to measure heat from places that are difficult. With a waterproof system, the sensor can also be deployed in wet areas and has a usable temperature range up to 125° C. It has 9 to 12 selectable resolutions and operates on a One Wire interface. The circuit also involves a data control/processing unit, which in this case is a Raspberry Pi. The Raspberry Pi includes support to DS18B20 sensors, which makes them compatible components. The design also features the .110 Low Profile Positive Lock connectors from TE Connectivity, which helps on contact retention between the sensors and the circuit. The connector reduces mating force and enhances safety and reliability of the mated pair with positive lock design. It also improves ease of assembly with low profile ergonomic housing design and reduced insertion force.
The Raspberry Pi has no ADC, however, the sensor has its own ADC that converts analog into digital signals. The data travels from the sensor to an IO pin in the raspberry pi for processing. The pull-up resistor in the circuit provides the stability and reliability of data transfer. The output of the circuit is fairly precise with ±0.5°C Accuracy from -10°C to +85°C. The circuit can be operated with a power source of 3.0V to 5.5V.The circuit can be modified through adding more sensors in which add more functionality in the system. Additional DS18B20 sensors can also be added in parallel using only a single pull-up resistor.