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 temperature sensor uses a DS18B20 chip, has a working temperature range of -55°C to +105°C, a temperature accuracy of -10°C to +80°C, and an error of 0.5°C; it is made of three-core sheathed wire conductor and is packaged using epoxy resin perfusion.