Analog Devices Inc./Maxim Integrated DS18B20U+

Overview

DS18B20U+ from Maxim Integrated (now Analog Devices) is a programmable-resolution 1-Wire digital thermometer with parasitic power capability, measuring -55°C to +125°C with ±0.5°C accuracy from -10°C to +85°C, and featuring nonvolatile alarm thresholds and unique 64-bit ROM addressing for multidrop bus operation in distributed temperature sensing systems.

For engineers reviewing the DS18B20U+ datasheet, DS18B20U+ pinout, DS18B20U+ application, or DS18B20U+ equivalent, key selection considerations include 1-Wire interface compatibility, parasitic vs. VDD-powered operation, 9–12-bit resolution tradeoffs, alarm search functionality, and µSOP-8 package mechanical constraints for high-density PCB layouts.

Technical Context

The DS18B20U+ implements a fully integrated 1-Wire interface using open-drain DQ signaling with weak pullup support and optional strong pullup control during temperature conversion or EEPROM write cycles. Its internal architecture includes a bandgap-based temperature sensor, 16-bit sign-extended two's complement output register, and scratchpad memory with EEPROM-backed TH/TL alarm registers and configuration byte.

It supports two power modes: local VDD supply (pin 3 connected to 3.0–5.5V) or parasite power (pin 3 grounded), where energy is harvested via DQ during bus high periods and stored on an internal capacitor (CPP). Alarm detection uses real-time comparison of converted temperature against user-programmed 8-bit TH/TL thresholds, with flag status accessible via Alarm Search [ECh] command.

Key Specifications

Pinout & Package

DS18B20U+ is housed in an 8-pin µSOP package (2.0mm × 2.5mm, 0.5mm pitch), optimized for space-constrained PCBs. Pin 1 = DQ (bidirectional 1-Wire data/power), Pin 4 = GND, Pin 8 = VDD (must be grounded for parasite power mode); pins 2,3,5,6,7 are no-connect.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS18B20+T, DS18B20U+ offers superior PCB density and automated assembly compatibility; compared with MAX31820M+, it provides cost-optimized performance for standard industrial temperature ranges without requiring firmware changes.

Availability

DS18B20U+ is available at Aetrix Electronics and suitable for HVAC environmental controls, industrial process monitoring, and consumer appliance thermal protection requiring stable component supply across long production lifecycles.

Supply support for DS18B20U+ 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 acquired Maxim Integrated in 2021 and maintains full technical and supply chain continuity for legacy Maxim sensor products including the DS18B20 series.

The DS18B20U+ belongs to Maxim's 1-Wire sensor family, designed specifically for low-cost, wire-efficient distributed temperature measurement in resource-constrained embedded systems.

FAQ

What is the difference between DS18B20U+ and DS18B20+?

The DS18B20U+ is the µSOP-8 packaged variant of the DS18B20 digital thermometer, while DS18B20+ typically refers to the SO-8 or TO-92 versions. All share identical electrical specifications, 1-Wire protocol, and temperature performance, but DS18B20U+ uses a smaller 2.0mm × 2.5mm footprint optimized for high-density PCBs. The DS18B20U+ part number specifically denotes the µSOP package with lead-free, RoHS-compliant finish.

Can DS18B20U+ operate without an external power supply?

Yes, DS18B20U+ supports parasite power mode, drawing energy from the 1-Wire bus via the DQ pin during high periods and storing charge on an internal capacitor. In this mode, VDD (pin 8) must be grounded, and a strong pullup (e.g., MOSFET-switched 3.3V/5V rail) is required during temperature conversions to supply up to 1.5mA peak current. This eliminates the need for separate VDD traces in remote sensor nodes.

How does the DS18B20U+ alarm function work in practice?

The DS18B20U+ stores user-defined upper (TH) and lower (TL) temperature thresholds in nonvolatile EEPROM. After each conversion, it compares the result and sets an internal alarm flag if outside bounds. The host MCU can then issue an Alarm Search [ECh] command to identify all DS18B20U+ devices on the bus with active alarms-enabling rapid fault isolation in large-scale deployments without individual address polling.

What is the maximum number of DS18B20U+ sensors on a single 1-Wire bus?

There is no hard limit on DS18B20U+ count per 1-Wire bus due to its unique 64-bit ROM addressing. Practical limits depend on bus capacitance, pullup strength, and cable length: up to 50–100 units are reliably supported with proper 4.7kΩ pullup and twisted-pair cabling. Each DS18B20U+ responds only to commands containing its specific ROM code, preventing address conflicts in multidrop configurations.

Does DS18B20U+ require external components for basic operation?

No external components are required for DS18B20U+ basic operation beyond a 4.7kΩ pullup resistor on the DQ line. Unlike analog sensors, it integrates the temperature transducer, ADC, EEPROM, and 1-Wire interface into a single die. No calibration resistors, op-amps, or voltage references are needed-reducing BOM count and layout complexity while maintaining ±0.5°C accuracy across its primary operating range.