DS18B20 Programmable Resolution 1-Wire Digital Thermometer IC

The DS18B20 digital thermometer designed explicitly to measures temperatures from 9 to 12 bits in Celsius and has a nonvolatile alarm function with user-programmable upper and lower trigger points. The DS18B20 communicates with a central CPU through a 1-Wire bus, which requires only one data line (and ground) by definition. Furthermore, the DS18B20 may get power directly from the data line (“parasitic power”), removing the need for an external power supply.

Each DS18B20 has its own 64-bit serial code, allowing several DS18B20s to share a single 1-Wire bus. As a result, controlling a large number of DS18B20s with a single CPU is simple. HVAC environmental controls, temperature monitoring systems inside buildings, equipment, or machinery, and process monitoring and control systems are among applications that can benefit from this functionality.

Furthermore, the device’s unique serial code is stored in the 64-bit ROM. The 2-byte temperature register in the scratchpad memory holds the digital output from the temperature sensor. The 1-byte upper and lower alarm trigger registers (TH and TL), as well as the 1-byte configuration register, are also accessible via the scratchpad. As a result, the user can set the resolution of the temperature-to-digital conversion to 9, 10, 11, or 12 bits using the configuration register. Because the TH, TL, and configuration registers are nonvolatile (EEPROM), data is retained even when the device is turned off. The DS18B20 1-Wire bus protocol uses a single control signal to achieve bus communication. Because all devices are connected to the bus via a 3-state or open-drain port, the control line requires a weak pullup resistor (the DQ pin in the case of the DS18B20).

Applications

•  Thermostatic Controls
•  Industrial Systems
•  Consumer Products
• Thermometers
•  Thermally Sensitive Systems