Analog Devices Inc./Maxim Integrated DS1825U+T&R

Overview

DS1825U+T&R from Maxim Integrated is a programmable-resolution 1-Wire digital thermometer with 4-bit location address, operating from -55°C to +125°C with ±0.5°C accuracy over -10°C to +85°C, 9–12-bit user-selectable resolution, and parasitic or VDD-powered operation in an 8-pin µSOP package - used for distributed thermal monitoring in HVAC, industrial control, and embedded systems.

For engineers reviewing the DS1825U+T&R datasheet, DS1825U+T&R pinout, DS1825U+T&R application, or DS1825U+T&R equivalent, key selection considerations include 1-Wire bus compatibility, NV alarm register programming, AD0–AD3 hard-wired address configuration, parasite-power timing constraints (e.g., strong pullup during 750ms 12-bit conversion), and lead-free µSOP tape-and-reel packaging for automated assembly.

Technical Context

The DS1825U+T&R implements a Dallas 1-Wire interface using open-drain DQ with weak pullup (4.7kΩ) and optional strong pullup for parasite-power temperature conversions. Its internal architecture integrates a 64-bit ROM for unique device identification, scratchpad SRAM with NV EEPROM for TH/TL alarm thresholds and configuration register, and a 12-bit sign-extended two's complement temperature register.

Resolution is set via R0/R1 bits in the configuration register (default 12-bit), directly determining conversion time (93.75ms to 750ms) and LSB step size (0.5°C to 0.0625°C). The 4-bit AD0–AD3 pins are sampled at power-up to encode sensor location, enabling up to 16 uniquely identifiable nodes on a single bus without software lookup tables.

Key Specifications

Pinout & Package

DS1825U+T&R is housed in an 8-pin µSOP (micro Small Outline Package) with 0.5mm pitch, lead-free finish, and tape-and-reel delivery optimized for automated placement.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 1-Wire digital thermometer applications.

Compared with DS1825U+T&R, DS18B20+T&R offers tighter full-range accuracy but removes hardware address flexibility, while MAX31820+T&R retains pinout compatibility but sacrifices temperature range and nonvolatile alarm capability - making DS1825U+T&R optimal for scalable, high-temp, location-aware thermal networks.

Availability

DS1825U+T&R is available at Aetrix Electronics and suitable for industrial process monitoring, HVAC zone control, and server rack thermal management requiring stable component supply, RoHS-compliant packaging, and long-term lifecycle support.

Supply support for DS1825U+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

Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in precision analog, mixed-signal, and power management ICs for industrial, communications, and computing applications.

The DS1825U+T&R belongs to Maxim's 1-Wire temperature sensor family, designed specifically for distributed, low-wiring-count thermal sensing in environments where space, power, and scalability are critical constraints.

FAQ

What is the maximum operating temperature of the DS1825U+T&R?

The DS1825U+T&R operates from -55°C to +125°C. Its specified accuracy of ±0.5°C applies between -10°C and +85°C; outside this range, accuracy degrades to ±2°C. Parasite power operation is not recommended above +100°C due to increased leakage current affecting communication reliability - for high-temperature applications, external VDD supply is required to maintain DS1825U+T&R functionality.

How does the DS1825U+T&R handle power supply in parasitic mode?

In parasite power mode, the DS1825U+T&R draws current through the DQ pin during bus-high periods and stores charge on an internal capacitor (CPP) to sustain operation during bus-low intervals. A strong pullup (e.g., MOSFET-switched rail) must be enabled within 10µs of issuing Convert T [44h] and held for the full 750ms (12-bit) conversion duration. The DS1825U+T&R requires VDD to be grounded in this mode, and its supply voltage remains constrained to 3.0–3.7V.

Can the DS1825U+T&R be used as a direct replacement for the DS1822?

Yes - the DS1825U+T&R is software compatible with the DS1822, sharing identical 1-Wire command structure, scratchpad memory map, and timing parameters. However, the DS1825U+T&R adds AD0–AD3 hardware address pins and enhanced NV alarm register functionality not present in the DS1822. No firmware changes are needed, but leveraging the new features requires updated host code to configure and read the address bits.

What is the purpose of the AD0–AD3 pins on the DS1825U+T&R?

The AD0–AD3 pins on the DS1825U+T&R provide a 4-bit hardware-encoded location identifier, allowing up to 16 uniquely addressable sensors on a single 1-Wire bus without relying solely on 64-bit ROM codes. These pins are sampled at power-up and reflected in bits 0–3 of the configuration register. When used with parasite power, they must be tied to DQ or GND; with VDD power, they must connect to VDD or GND - floating connections yield indeterminate values.

Does the DS1825U+T&R support alarm functionality, and how is it implemented?

Yes - the DS1825U+T&R includes nonvolatile TH and TL registers that store user-defined upper and lower temperature thresholds. After each conversion, the measured value is compared against these limits; if exceeded, an internal alarm flag is set. The host can then issue the Alarm Search [ECh] command to discover only those DS1825U+T&R devices currently in alarm state - reducing bus traffic versus polling all nodes individually.