DS18B20Z datasheet by Dallas Semiconductor

DS18B20Z Frequently Asked Questions (FAQs)

• What is the maximum number of DS18B20Z devices that can be connected to a single bus?
  Theoretically, up to 255 devices can be connected to a single bus, but in practice, the maximum number is limited by the bus capacitance and the pull-up resistor value. A good rule of thumb is to limit the number of devices to 10-20 per bus.
• How do I handle multiple devices with the same ROM code?
  In rare cases, multiple DS18B20Z devices may have the same ROM code. To handle this, use a unique alias or nickname for each device, or use a combination of the ROM code and the device's physical location to identify it.
• What is the minimum and maximum cable length for the 1-Wire bus?
  The minimum cable length is not specified, but in practice, it's recommended to have at least 10 cm (4 inches) of cable between devices. The maximum cable length depends on the bus speed, but a good rule of thumb is to limit it to 100 meters (330 feet) at 14.4 kbps and 20 meters (66 feet) at 115.2 kbps.
• Can I use a 5V power supply for the DS18B20Z?
  No, the DS18B20Z is a 3.3V device and should not be powered from a 5V supply. Using a 5V supply can damage the device. Use a 3.3V power supply or a voltage regulator to ensure safe operation.
• How do I ensure reliable communication over the 1-Wire bus?
  To ensure reliable communication, use a strong pull-up resistor (e.g., 2.2 kΩ), keep the bus capacitance low, and use a high-quality cable with a twisted pair or shielded wire. Also, implement error checking and retries in your software to handle occasional errors.