Analog Devices Inc./Maxim Integrated MAX31850TATB+T

Overview

MAX31850TATB+T from Maxim Integrated is a cold-junction compensated, 1-Wire thermocouple-to-digital converter optimized for Type T thermocouples, delivering 14-bit resolution (0.25°C), ±2°C accuracy over –270°C to +400°C, and integrated open/short fault detection. It operates from 3.0V–3.7V supply, supports parasite power, and enables distributed temperature sensing in industrial HVAC and medical equipment.

For engineers reviewing the MAX31850TATB+T datasheet, MAX31850TATB+T pinout, MAX31850TATB+T application, or MAX31850TATB+T equivalent, key selection criteria include its Type T thermocouple calibration, 1-Wire multdrop capability, cold-junction compensation accuracy (±2°C at –270°C to +400°C), parasitic power operation, and AD0–AD3 address pin mapping for location-based sensor networks.

Technical Context

The MAX31850TATB+T integrates a precision 14-bit ADC, internal cold-junction temperature sensor (±2°C error), and dedicated signal conditioning for Type T thermocouples (52.18 µV/°C nominal sensitivity). Its conversion architecture performs three synchronized operations: thermocouple voltage digitization, die temperature measurement, and fault detection (open, short-to-GND, short-to-VDD).

Communication occurs exclusively via a single-wire 1-Wire bus (DQ pin) with strict timing requirements: tSLOT = 60–120 µs, tCONV = 72–100 ms, and strong pullup activation required during conversion. Power options include local VDD supply or parasite power via DQ, with VDD tied to GND in the latter mode.

Key Specifications

Pinout & Package

TDFN-EP (3mm × 4mm, 10-pin, exposed pad); pin-compatible with MAX31850 family; EP must be connected to GND for thermal and EMI performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar thermocouple digitizer applications.

Compared with MAX31856AUG+T and AD8495ARZ, the MAX31850TATB+T uniquely combines Type T-specific calibration, 1-Wire daisy-chain capability, and autonomous fault reporting in a single TDFN package-enabling rapid deployment of scalable, low-wiring-count temperature networks without host-side signal processing overhead.

Availability

MAX31850TATB+T is available at Aetrix Electronics and suitable for industrial process monitoring, HVAC system control, medical sterilization equipment, and appliance temperature safety requiring stable component supply and long-term lifecycle support.

Supply support for MAX31850TATB+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 power management ICs for demanding industrial, medical, and automotive applications.

The MAX31850 series was developed specifically to simplify thermocouple-based temperature measurement by integrating cold-junction compensation, fault detection, and 1-Wire communication into a single chip-targeting distributed sensing in space-constrained, low-power, and high-reliability systems.

FAQ

What thermocouple types does the MAX31850TATB+T support?

The MAX31850TATB+T is factory-calibrated exclusively for Type T thermocouples (copper/constantan), covering –270°C to +400°C. It is not configurable for other types; MAX31850K, MAX31850J, etc., are separate variants. Using a non-Type T thermocouple with MAX31850TATB+T yields uncorrected errors exceeding ±10°C due to mismatched sensitivity (52.18 µV/°C) and linearization.

How does the MAX31850TATB+T handle cold-junction compensation?

The MAX31850TATB+T measures its own die temperature with an internal sensor (±2°C accuracy, 0.0625°C resolution), then algebraically adds that value to the raw thermocouple voltage-derived temperature. This fully compensates for ambient variations at the cold junction. The result is stored in Bytes 0–1 of the scratchpad as a cold-junction-compensated reading.

Can the MAX31850TATB+T operate without an external power supply?

Yes-the MAX31850TATB+T supports parasite power: it draws operating current from the 1-Wire bus via the DQ pin when the bus is high, storing charge on an internal capacitor (CPP). However, VDD must be tied to GND, and a strong pullup (e.g., MOSFET-switched rail) is mandatory during the 72–100 ms conversion period to supply peak current (~1.5 mA).

What fault conditions does the MAX31850TATB+T detect, and how are they reported?

The MAX31850TATB+T detects open thermocouple, short-to-GND, and short-to-VDD on T+/T– inputs. Fault status is encoded in Bits 0–2 of the internal temperature LSB (Scratchpad Byte 2): Bit 0 = open, Bit 1 = short-to-GND, Bit 2 = short-to-VDD. A fault also sets Bit 0 of the thermocouple temperature LSB (Byte 0) to flag corrupted data.

How are the AD0–AD3 pins used in the MAX31850TATB+T?

The AD0–AD3 pins (Pins 6–9) are hardwired address inputs that encode a 4-bit location ID (0–15). Their logic states (GND = 0, DQ = 1) are latched at power-up and mirrored in Bits 3–0 of Scratchpad Byte 4 (Configuration Register). This allows firmware to identify physical sensor placement without relying solely on 64-bit ROM addresses.