Analog Devices Inc./Maxim Integrated DS18B20EVSYS1#

The DS18B20, produced by Analog Devices Inc. (now part of Maxim Integrated), is a programmable resolution 1-Wire digital thermometer. This device is designed for high-precision temperature monitoring with minimal connections, making it ideal for multisensor systems. The DS18B20 can measure temperatures with a resolution of 9-bit to 12-bit Celsius and features an alarm function with nonvolatile user-programmable upper and lower trigger points. It communicates over a 1-Wire bus, requiring only one data line and ground for communication with a central microprocessor, and can derive power directly from the data line (parasite power) or from an external supply.

• High-Precision Temperature Measurements: The DS18B20 provides accurate temperature readings with resolutions from 9-bit to 12-bit Celsius.
• 1-Wire Communication: Requires only one data line and ground for communication, simplifying wiring and reducing the number of connections needed.
• Parasite Power Capability: Can derive power directly from the data line, eliminating the need for an external power supply in many applications.
• Unique Identifier: Each DS18B20 has a unique 64-bit serial code, allowing multiple devices to function on the same 1-Wire bus.
• Alarm Function: Features nonvolatile user-programmable upper and lower temperature trigger points for alarm notifications.
• Memory and Configuration: Includes a scratchpad RAM and nonvolatile EEPROM for storing temperature triggers and configuration data.

• HVAC Environmental Controls: Ideal for temperature monitoring and control in heating, ventilation, and air conditioning systems.
• Building and Equipment Monitoring: Suitable for monitoring temperatures inside buildings, equipment, or machinery.
• Process Monitoring and Control: Used in various industrial processes that require precise temperature monitoring and control.
• Multisensor Systems: Can be used in systems where multiple temperature sensors are needed, leveraging its unique identifier and 1-Wire bus capability.

1. What is the temperature resolution of the DS18B20?

   The DS18B20 can measure temperatures with a resolution of 9-bit to 12-bit Celsius.

2. How does the DS18B20 communicate with a microprocessor?

   The DS18B20 communicates over a 1-Wire bus, requiring only one data line and ground for communication.

3. Can the DS18B20 operate without an external power supply?
4. What is the unique feature of each DS18B20 device?

   Each DS18B20 has a unique 64-bit serial code, allowing multiple devices to function on the same 1-Wire bus.

5. What is the purpose of the alarm function in the DS18B20?

   The alarm function allows for nonvolatile user-programmable upper and lower temperature trigger points for alarm notifications.

6. How does the DS18B20 store and retrieve configuration data?

   The DS18B20 uses a scratchpad RAM and nonvolatile EEPROM to store and retrieve temperature triggers and configuration data.

7. What are some common applications of the DS18B20?

   The DS18B20 is commonly used in HVAC environmental controls, building and equipment monitoring, process monitoring and control, and multisensor systems.

8. How many devices can be addressed on one 1-Wire bus?

   The number of devices that can be addressed on one 1-Wire bus is virtually unlimited due to the unique 64-bit serial code of each DS18B20.

9. What is the significance of the CRC byte in the DS18B20's ROM code?

   The CRC byte is a cyclic redundancy check byte calculated from the first 56 bits of the ROM code, ensuring data integrity.

10. How does the DS18B20 signal its power supply scheme to the bus master?

    The DS18B20 signals its power supply scheme by sending a “0” on the 1-Wire bus if it is parasite powered and a “1” if it is powered from the VDD pin.