Analog Devices Inc./Maxim Integrated DS18S20+T&R

Overview

DS18S20+T&R from Maxim Integrated is a high-precision 1-Wire digital thermometer IC with 9-bit resolution, ±0.5°C accuracy from −10°C to +85°C, and operating range of −55°C to +125°C. It functions as a self-contained temperature sensor node on a single-wire bus, supporting parasitic power mode (DQ + GND only) and featuring nonvolatile alarm thresholds (TH/TL) for autonomous thermal monitoring in distributed systems.

For engineers reviewing the DS18S20+T&R datasheet, DS18S20+T&R pinout, DS18S20+T&R application, or DS18S20+T&R equivalent, key selection considerations include 1-Wire multidrop capability, unique 64-bit ROM addressing, parasite-power compatibility, and EEPROM-stored alarm trigger values requiring no external components.

Technical Context

The DS18S20+T&R implements a direct-to-digital temperature sensor with 9-bit output (0.5°C LSB), internal scratchpad memory (9 bytes), and dedicated TH/TL alarm registers stored in nonvolatile EEPROM. Its 1-Wire interface uses open-drain DQ signaling with strict timing slots (tSLOT = 60–120 µs) and requires a weak pullup resistor (typically 4.7 kΩ) for bus idle state.

It supports two power modes: local VDD supply (3.0–5.5 V) or parasite power via DQ, where internal capacitor CPP sustains operation during low-bus periods. Strong pullup activation (within 10 µs) is mandatory during temperature conversion (tCONV = 750 ms) or EEPROM write (tWR = 2–10 ms) under parasite power.

Key Specifications

Pinout & Package

DS18S20+T&R is supplied in TO-92 package (3-pin, through-hole), with pin 1 = GND, pin 2 = DQ (open-drain 1-Wire I/O), pin 3 = VDD (optional; must be grounded in parasite power mode).

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS18B20+T&R and MAX31820MUA+, the DS18S20+T&R delivers proven reliability and lowest BOM cost for 0.5°C-resolution thermal monitoring, while maintaining identical 1-Wire protocol compliance and TO-92 mechanical fit-making it ideal for high-volume, space-constrained, or legacy-compatible deployments.

Availability

DS18S20+T&R is available at Aetrix Electronics and suitable for HVAC environmental controls, industrial process monitoring systems, and consumer appliance thermal management requiring stable component supply and long-term lifecycle support.

Supply support for DS18S20+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 digital ICs for industrial, communications, and computing applications.

The DS18S20+T&R belongs to Maxim's 1-Wire temperature sensor family, designed specifically for distributed, low-wiring-cost thermal sensing in harsh or space-constrained environments.

FAQ

What is the maximum number of DS18S20+T&R sensors that can operate on a single 1-Wire bus?

There is no hard limit-the DS18S20+T&R uses a unique 64-bit ROM serial code for device identification, enabling hundreds of units on one bus. Practical limits depend on bus capacitance, pullup strength, and cable length; typical installations support 20–50 sensors with proper 4.7 kΩ pullup and twisted-pair wiring. The DS18S20+T&R's multidrop capability eliminates address conflicts inherent in I²C or SPI sensors.

Does DS18S20+T&R require an external power supply, or can it run on parasite power alone?

The DS18S20+T&R supports both modes: local VDD supply (3.0–5.5 V) or parasite power via the DQ pin. In parasite mode, VDD must be grounded. Parasite power eliminates the need for a second wire but requires a strong pullup (e.g., MOSFET-switched rail) during temperature conversion (750 ms) and EEPROM writes (up to 10 ms) to meet the 1.5 mA peak current demand.

How accurate is DS18S20+T&R across its full temperature range?

The DS18S20+T&R guarantees ±0.5°C accuracy from −10°C to +85°C-the most commonly used industrial range. Outside this band, accuracy degrades to ±2°C from −55°C to +125°C. Drift is limited to ±0.2°C after 1000 hours at +125°C, making it suitable for long-life embedded applications where recalibration is impractical.

Can DS18S20+T&R store custom alarm thresholds, and do they persist after power loss?

Yes-the DS18S20+T&R includes nonvolatile EEPROM storage for upper (TH) and lower (TL) alarm trigger values. These settings retain data for ≥10 years at −55°C to +55°C and survive unlimited power cycles. Thresholds are written via Write Scratchpad and copied to EEPROM using Copy Scratchpad commands-no external memory or firmware storage needed.

What is the function of the CRC byte in DS18S20+T&R's scratchpad memory?

The CRC byte (scratchpad byte 8) provides error detection for the first 8 bytes of scratchpad data (temperature, TH/TL, COUNT registers). The DS18S20+T&R calculates it using polynomial X⁸ + X⁵ + X⁴ + 1. Host microcontrollers must recalculate CRC from received data and compare it to this byte to verify transmission integrity-critical for reliable remote sensing in noisy industrial environments.