The DS18B20 does not require an external power source to function. The device is powered when the data line DQ is high. The internal capacitor (Spp) charges when the bus is pulled high, and the capacitor powers the device when the bus is pulled low. "Parasitic power" is the term used to describe this method of 1-Wire bus device powering.
The DS18B20 is a popular digital temperature sensor with the features of small size, minimal hardware overhead, strong anti-interference capabilities, and high precision. It outputs digital signals. The DS18B20 digital temperature sensor is simple to wire and is packaged in a variety of ways, including pipeline, screw, magnet adsorption, stainless steel, and numerous model options.
The temperature readings from the DS18B20 temperature sensor are 9-bit (binary), suggesting that the device's temperature data is either sent to the DS18B20 temperature sensor via the single-line interface or that it is sent out from the DS18B20 temperature sensor. As a result, just one line (plus ground) is required to connect the host CPU to the DS18B20 temperature sensor, and the data line itself can act as the sensor's power source in place of an external power source.