Analog Devices Inc./Maxim Integrated DS18B20+

Overview

DS18B20+ from Maxim Integrated (now Analog Devices) is a programmable-resolution 1-Wire digital thermometer with ±0.5°C accuracy from –10°C to +85°C, operating from –55°C to +125°C, and featuring nonvolatile alarm thresholds and parasite power capability. It functions as a self-contained temperature sensor node in distributed monitoring systems, requiring only one data line and ground for communication and power delivery.

For engineers reviewing the DS18B20+ datasheet, DS18B20+ pinout, DS18B20+ application, or DS18B20+ equivalent, key selection considerations include 1-Wire multidrop support, parasitic vs. VDD-powered operation, 9–12-bit resolution tradeoffs, alarm search functionality, and TO-92/SO/µSOP package compatibility with legacy thermal sensing layouts.

Technical Context

The DS18B20+ implements a fully integrated 1-Wire interface using an open-drain DQ pin with internal pullup control logic and parasite power capacitor charging circuitry. Its on-chip temperature sensor feeds a 16-bit sign-extended two's complement register, with resolution configurable via EEPROM-stored bits R0/R1 in the configuration register.

Alarm detection operates by comparing each conversion result against user-programmed TH/TL registers stored in nonvolatile EEPROM; the Alarm Search [ECh] command enables bus-level identification of devices exceeding thresholds without individual addressing. The device supports both strong-pullup-assisted parasite power mode and conventional VDD-supplied operation, with automatic power-source detection via Read Power Supply [B4h].

Key Specifications

Pinout & Package

DS18B20+ is available in three industry-standard packages: 3-pin TO-92 (through-hole), 8-pin SO (150 mil), and 8-pin µSOP (surface-mount). Pin functions are identical across variants; TO-92 is most common for prototyping and field-deployed sensors.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar digital thermometer applications.

Compared with DS18B20+, DS1820Z+ lacks resolution programming and parasite power - limiting deployment flexibility - while MAX31820 delivers measurable accuracy and noise immunity gains at minimal layout impact, making it the preferred upgrade path for new designs targeting <±0.3°C performance.

Availability

DS18B20+ is available at Aetrix Electronics and suitable for HVAC environmental controls, industrial equipment monitoring, and consumer appliance thermal management requiring stable component supply and long-term lifecycle support.

Supply support for DS18B20+ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices (via acquisition of Maxim Integrated) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets.

The DS18B20+ belongs to Maxim's 1-Wire sensor family, designed specifically for low-cost, wire-efficient distributed temperature measurement in harsh or space-constrained environments.

FAQ

What is the maximum number of DS18B20+ sensors that can operate on a single 1-Wire bus?

The DS18B20+ uses a unique 64-bit ROM address, enabling theoretically unlimited devices on one bus. In practice, signal integrity limits reliable operation to ~50–100 units depending on bus length, pullup strength, and noise environment. For large deployments, use active repeaters or segment isolation to maintain timing margins and avoid collision errors during ROM searches.

Does DS18B20+ require an external power supply, or can it run solely on parasite power?

DS18B20+ supports both modes: parasite power (DQ + GND only) and external VDD supply (3.0–5.5V). Parasite power eliminates a dedicated rail but requires a strong pullup during temperature conversions and EEPROM writes. VDD mode simplifies design by removing timing-critical pullup switching and is mandatory above +100°C due to leakage current limitations in parasite mode.

How does the DS18B20+ alarm function work, and how is it triggered?

The DS18B20+ compares each temperature reading against user-programmed TH (high) and TL (low) thresholds stored in nonvolatile EEPROM. If the value falls ≤ TL or ≥ TH, an internal alarm flag is set. The master detects active alarms across all devices using the Alarm Search [ECh] command - no individual polling required - enabling rapid fault localization in multi-sensor systems.

What is the resolution configuration mechanism for DS18B20+, and how does it affect conversion time?

DS18B20+ resolution is set via R1/R0 bits in the configuration register (byte 4 of scratchpad), stored in EEPROM. Options are 9-bit (0.5°C, 93.75ms), 10-bit (0.25°C, 187.5ms), 11-bit (0.125°C, 375ms), or 12-bit (0.0625°C, 750ms). Default is 12-bit at power-up. Higher resolution increases precision but linearly extends conversion latency - critical for battery-powered or high-throughput systems.

Can DS18B20+ be used in environments exceeding +100°C, and what are the constraints?

DS18B20+ is rated for operation up to +125°C, but parasite power mode is not recommended above +100°C due to increased leakage currents that degrade bus communication reliability. For high-temperature applications (e.g., industrial ovens, engine bays), use VDD-powered operation with proper thermal derating and ensure PCB layout minimizes self-heating effects on measurement accuracy.