Analog Devices Inc./Maxim Integrated MAX31850EATB+

Overview

MAX31850EATB+ from Maxim Integrated is a cold-junction compensated, 1-Wire thermocouple-to-digital converter optimized for E-type thermocouples. It delivers 14-bit resolution (0.25°C), supports thermocouple temperature range from –270°C to +1000°C, and integrates on-chip cold-junction sensing with ±2°C accuracy over –40°C to +125°C ambient. It enables distributed temperature monitoring in industrial sensor nodes where minimal wiring and parasitic power operation are critical.

For engineers reviewing the MAX31850EATB+ datasheet, MAX31850EATB+ pinout, MAX31850EATB+ application, or MAX31850EATB+ equivalent, key selection considerations include its E-type thermocouple calibration, 1-Wire parasitic-power capability, integrated open/short fault detection, 10-pin TDFN-EP package, and location-addressing via AD0–AD3 pins.

Technical Context

The MAX31850EATB+ implements a dedicated analog front-end with programmable gain and offset correction tailored to E-type thermocouples (76.373 µV/°C nominal sensitivity), paired with a 14-bit ADC and internal cold-junction temperature sensor. Its conversion architecture performs three synchronized operations per cycle: thermocouple voltage digitization, die temperature measurement, and fault detection (open, short-to-VDD, short-to-GND).

Communication occurs exclusively over a single-wire 1-Wire bus (DQ) with strict timing compliance (tSLOT = 60–120 µs, tRSTL ≥ 480 µs). Power delivery supports dual modes: local VDD supply (3.0–3.7 V) or parasite power via DQ with strong pullup required during 72–100 ms conversions.

Key Specifications

Pinout & Package

MAX31850EATB+ uses a 10-pin 3mm × 4mm TDFN-EP package with exposed pad (EP) for thermal dissipation. Pin 10 (DNC) is unconnected and must remain floating; EP may be connected to GND for improved thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX31850EATB+, MAX31855KASA+ trades 1-Wire simplicity and E-type support for SPI speed and K-type precision, while AD8495ARZ shifts responsibility for digitization and cold-junction compensation to external components - increasing BOM count and calibration burden.

Availability

MAX31850EATB+ is available at Aetrix Electronics and suitable for industrial process monitoring, HVAC system sensors, medical sterilization equipment, and appliance temperature control requiring stable component supply and long-term production continuity.

Supply support for MAX31850EATB+ 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 and mixed-signal ICs for demanding industrial, medical, and communications applications.

The MAX31850 series targets distributed temperature sensing systems requiring minimal interconnect, self-identifying nodes, and direct thermocouple interfacing - emphasizing reliability, calibration integrity, and ease of integration in harsh environments.

FAQ

What thermocouple types does the MAX31850EATB+ support?

The MAX31850EATB+ is factory trimmed and calibrated exclusively for E-type thermocouples, leveraging a nominal sensitivity of 76.373 µV/°C. It does not support K-, J-, N-, T-, R-, or S-type thermocouples - those require other variants such as MAX31850K or MAX31851R. Using an E-type thermocouple ensures full accuracy within the specified error bands (±1°C to ±5°C depending on temperature range).

Can the MAX31850EATB+ operate without an external power supply?

Yes, the MAX31850EATB+ supports parasite power mode, drawing energy from the 1-Wire bus via the DQ pin. In this mode, VDD must be connected to GND. However, a strong pullup (e.g., MOSFET-switched rail) is mandatory during the 72–100 ms temperature conversion period to supply peak current (~1.5 mA). Parasite power is not recommended above +100°C due to leakage-related communication instability.

How does the MAX31850EATB+ detect thermocouple faults?

The MAX31850EATB+ integrates dedicated fault-detection circuitry that autonomously checks for open circuits, shorts to GND, and shorts to VDD on the T+ and T– inputs. Fault status is encoded in bits 0–2 of scratchpad byte 2: bit 0 = open, bit 1 = short-to-GND, bit 2 = short-to-VDD. This occurs during every conversion cycle and requires no host intervention or additional external components.

What is the purpose of the AD0–AD3 pins on the MAX31850EATB+?

The AD0–AD3 pins on the MAX31850EATB+ provide hardware-programmable location addressing: each pin reads as logic 0 (GND) or 1 (DQ or ≤10 kΩ pullup) and is reflected in bits [3:0] of the configuration register (scratchpad byte 4). This allows up to 16 uniquely identifiable physical locations per bus segment - simplifying commissioning, diagnostics, and firmware mapping in large-scale sensor deployments.

Does the MAX31850EATB+ include cold-junction compensation?

Yes, the MAX31850EATB+ integrates a precision on-die temperature sensor with ±2°C accuracy over –40°C to +100°C ambient, used to measure the cold-junction temperature adjacent to the T+/T– terminals. It applies real-time correction to the raw thermocouple voltage using E-type-specific linearization, delivering cold-junction-compensated temperature values directly in the scratchpad (bytes 0–1) without host-side computation.