Analog Devices Inc./Maxim Integrated MAX31851SATB+T

Overview

MAX31851SATB+T from Maxim Integrated is a cold-junction compensated, 1-Wire thermocouple-to-digital converter optimized for S-type thermocouples. It delivers 14-bit resolution (0.25°C), supports thermocouple temperature range from –50°C to +1768°C, achieves ±2°C accuracy over –50°C to +700°C, and integrates fault detection for open/shorted thermocouple leads. It is used in industrial furnace monitoring where remote, multi-node temperature sensing with minimal wiring is required.

For engineers reviewing the MAX31851SATB+T datasheet, MAX31851SATB+T pinout, MAX31851SATB+T application, or MAX31851SATB+T equivalent, key selection considerations include S-type thermocouple support, parasitic power capability, 1-Wire multdrop architecture, cold-junction compensation accuracy, and fault diagnostics for open/short conditions on T+/T– inputs.

Technical Context

The MAX31851SATB+T implements a dedicated analog front-end with programmable gain and offset correction tailored for S-type thermocouples (9.587 µV/°C nominal sensitivity), paired with a 14-bit ADC and internal die temperature sensor for cold-junction compensation. Its conversion architecture sequentially measures thermocouple voltage, internal junction temperature, and performs fault detection - all within a single 72–100 ms conversion cycle.

It operates exclusively via the 1-Wire interface (DQ pin), supporting both local VDD supply and parasite power modes. Four address pins (AD0–AD3) enable hardware-programmable location mapping, while the unique 64-bit ROM ID allows bus-level device enumeration without external addressing logic.

Key Specifications

Pinout & Package

TDFN-EP (3mm × 4mm, 10-pin) with exposed pad; pin 10 is DNC (Do Not Connect); EP has no internal connection and may be grounded or left floating.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar thermocouple-to-digital conversion applications.

Compared with MAX31850KATB+T and AD8495ARZ, the MAX31851SATB+T uniquely combines S-type thermocouple calibration, integrated 14-bit digitization, 1-Wire bus scalability, and autonomous fault reporting - eliminating external signal chain components and reducing BOM count in distributed high-temperature sensing.

Availability

MAX31851SATB+T is available at Aetrix Electronics and suitable for industrial furnace monitoring, HVAC duct sensing, medical autoclave validation, and power transformer hotspot monitoring requiring stable component supply and long-term lifecycle support.

Supply support for MAX31851SATB+T 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) designs precision analog, mixed-signal, and digital ICs for industrial, medical, and communications applications.

The MAX31851SATB+T belongs to Maxim's thermocouple interface product line, engineered specifically for high-accuracy, low-wiring-count temperature measurement in harsh environments using standard thermocouple types.

FAQ

What thermocouple types does the MAX31851SATB+T support?

The MAX31851SATB+T is factory trimmed and calibrated exclusively for S-type thermocouples. It is not compatible with K-, J-, N-, T-, R-, or E-type thermocouples. Using any other thermocouple type will result in significant measurement error due to mismatched sensitivity (9.587 µV/°C) and nonlinear compensation tables. The 'S' in the part number explicitly denotes S-type support.

Does the MAX31851SATB+T require an external power supply?

The MAX31851SATB+T supports two power modes: local VDD supply (3.0–3.7 V) or parasite power via the DQ pin. In parasite mode, VDD must be connected to GND, and a strong MOSFET pullup is mandatory during temperature conversions (72–100 ms). Parasite power is not recommended above +100°C due to leakage current effects.

How does the MAX31851SATB+T detect thermocouple faults?

The MAX31851SATB+T performs automatic fault detection during each conversion cycle. Bits 0–2 in scratchpad Byte 2 indicate open circuit (bit 0), short to GND (bit 1), or short to VDD (bit 2). These flags appear alongside the cold-junction temperature value and are reported in the same read transaction - enabling immediate diagnostic response without additional commands.

What is the role of the AD0–AD3 pins on the MAX31851SATB+T?

The AD0–AD3 pins on the MAX31851SATB+T provide hardware-programmable 4-bit location addressing. Their logic states (high/low) are latched at power-up and reflected in bits [3:0] of the Configuration Register (scratchpad Byte 4). This allows up to 16 uniquely identifiable nodes on a shared 1-Wire bus without software address assignment or EEPROM programming.

Can multiple MAX31851SATB+T devices share the same 1-Wire bus?

Yes - each MAX31851SATB+T contains a unique 64-bit ROM ID (family code 0x3B), enabling true multdrop operation. A single microcontroller can enumerate, address, and read temperature data from dozens of MAX31851SATB+T units on one data line and ground, using standard 1-Wire search and match ROM protocols without contention or collision.