Analog Devices Inc./Maxim Integrated DS18B20U+T&R

Overview

DS18B20U+T&R from Maxim Integrated (now Analog Devices) is a programmable-resolution 1-Wire digital thermometer in 8-pin µSOP package, measuring temperature from −55°C to +125°C with ±0.5°C accuracy over −10°C to +85°C, supporting parasite power operation and unique 64-bit ROM addressing for distributed sensing in HVAC and industrial monitoring systems.

For engineers reviewing the DS18B20U+T&R datasheet, DS18B20U+T&R pinout, DS18B20U+T&R application, or DS18B20U+T&R equivalent, key selection considerations include 1-Wire bus compatibility, parasitic vs. VDD-powered operation, 9–12-bit resolution configuration, alarm trigger register programmability, and µSOP package thermal performance in space-constrained PCB layouts.

Technical Context

The DS18B20U+T&R implements a fully integrated 1-Wire interface using open-drain DQ signaling with weak pullup (4.7kΩ), enabling multidrop bus topology without address decoding logic. Its internal architecture includes a bandgap-based temperature sensor, 2-byte signed two's complement temperature register, and EEPROM-backed TH/TL alarm registers plus configuration register.

It supports dual power modes: local VDD supply (pin 3) or parasite power via DQ (pin 1), requiring strong pullup during conversion (tCONV = 750ms max at 12-bit). The device uses Maxim's proprietary 1-Wire protocol with strict timing slots (tSLOT = 60–120µs), CRC-8 validation (X⁸+X⁵+X⁴+1), and automatic presence detection.

Key Specifications

Pinout & Package

DS18B20U+T&R is housed in an 8-pin µSOP package (2.0mm × 2.5mm, 0.5mm pitch), optimized for high-density PCB layouts and automated assembly. Pin 1 is DQ (bidirectional 1-Wire data/power), Pin 4 is GND, Pin 8 is VDD (must be grounded in parasite mode), and 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 DS18B20U+T&R, the SO-8 variant offers mechanical robustness and easier hand-soldering but increases board area by 3×; the MAX31820MUA+ delivers superior accuracy at room temperature but sacrifices operational range above +65°C and lacks extended −55°C support.

Availability

DS18B20U+T&R is available at Aetrix Electronics and suitable for HVAC environmental controls, industrial process monitoring, equipment thermal protection, and smart building sensor networks requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for DS18B20U+T&R 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 family.

The DS18B20U+T&R belongs to Maxim's 1-Wire sensor portfolio, designed specifically for distributed, low-wiring-cost temperature measurement in harsh and space-constrained environments where reliability and node scalability are critical.

FAQ

What power supply options does the DS18B20U+T&R support?

The DS18B20U+T&R supports two power configurations: local VDD supply (3.0V–5.5V applied to pin 8) or parasite power (pin 8 grounded, power drawn from DQ pin via 4.7kΩ pullup). In parasite mode, a strong pullup is required during temperature conversion (750ms max at 12-bit) to meet 1.5mA peak current demand. DS18B20U+T&R datasheets specify VIH ≥3.0V and VIL ≤0.8V under parasite conditions.

How does the DS18B20U+T&R achieve multidrop capability on a single 1-Wire bus?

The DS18B20U+T&R implements multidrop operation via its factory-lasered 64-bit ROM code (including 8-bit family code 0x28 and 48-bit unique serial number), allowing a single microcontroller to enumerate, address, and communicate with dozens of devices on one data line. The 1-Wire protocol uses time-slot arbitration and search algorithms (e.g., Search ROM [F0h]) to isolate individual devices without external addressing hardware. DS18B20U+T&R supports up to 100+ nodes in practice with proper bus termination.

What is the meaning of the resolution setting in the DS18B20U+T&R configuration register?

The DS18B20U+T&R configuration register (scratchpad byte 4, bits R1/R0) sets conversion resolution to 9, 10, 11, or 12 bits, directly determining temperature step size (0.5°C, 0.25°C, 0.125°C, or 0.0625°C) and maximum conversion time (93.75ms, 187.5ms, 375ms, or 750ms). Default power-up state is 12-bit. Higher resolution improves granularity but increases latency and power consumption during conversion. DS18B20U+T&R retains this setting in EEPROM across power cycles.

Can the DS18B20U+T&R operate reliably above +100°C?

The DS18B20U+T&R is rated for operation from −55°C to +125°C, but parasite power mode is not recommended above +100°C due to increased leakage currents that may disrupt 1-Wire communication. For sustained operation above +100°C, DS18B20U+T&R must be powered via VDD (pin 8) with a stable 3.0V–5.5V supply. At +125°C, standby current rises to ~3µA and thermometric error remains within ±2°C specification.

How does the DS18B20U+T&R alarm function work in practice?

The DS18B20U+T&R stores user-programmable upper (TH) and lower (TL) alarm thresholds in nonvolatile EEPROM. After each temperature conversion, it compares the result to TH/TL and sets an internal alarm flag if breached. Hosts detect active alarms using the Alarm Search [ECh] command, which returns only devices with flagged conditions-enabling rapid fault isolation in large sensor arrays. DS18B20U+T&R retains TH/TL values across power loss and supports runtime updates via Write Scratchpad [4Eh] and Copy Scratchpad [48h] commands.