Analog Devices Inc./Maxim Integrated MAX31850EATB+T

Overview

MAX31850EATB+T 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, achieves ±5°C total error over −40°C to +125°C ambient, and integrates fault detection for open/shorted thermocouple leads - used in industrial furnace monitoring where distributed, low-wiring-count temperature sensing is required.

For engineers reviewing the MAX31850EATB+T datasheet, MAX31850EATB+T pinout, MAX31850EATB+T application, or MAX31850EATB+T equivalent, key selection criteria include its parasitic-power capability, 10-pin TDFN-EP package with location-address inputs (AD0–AD3), E-type thermocouple calibration, cold-junction compensation accuracy (±2°C), and 72–100 ms conversion time - all critical for multi-sensor thermal management in space-constrained embedded systems.

Technical Context

The MAX31850EATB+T implements a dedicated 14-bit sigma-delta ADC with programmable gain optimized for E-type thermocouple sensitivity (76.373 µV/°C), coupled with an on-die temperature sensor for cold-junction compensation. Its internal switch matrix isolates thermocouple inputs during cold-junction measurement and fault detection phases.

Communication follows the 1-Wire protocol with read-only command set (e.g., Convert T [44h], Read Scratchpad [BEh]), requiring precise timing control - including mandatory strong pullup activation within 10 µs of conversion start and sustained for ≥100 ms. The device reports fault status via bits 0–2 in byte 2 of scratchpad memory.

Key Specifications

Pinout & Package

MAX31850EATB+T uses a 10-pin 3mm × 4mm TDFN-EP package with exposed pad (EP). Pin 10 is DNC; EP has no internal connection and may be grounded or left floating per layout requirements.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX31855KASA+ and AD8495ARZ, the MAX31850EATB+T uniquely combines E-type calibration, 1-Wire scalability, parasitic power, and integrated fault reporting - making it the only option for cost-sensitive, wiring-minimized, multi-node E-thermocouple systems requiring autonomous diagnostics.

Availability

MAX31850EATB+T is available at Aetrix Electronics and suitable for industrial furnace monitoring, HVAC duct sensing, medical sterilization validation, and appliance oven control requiring stable component supply across extended production lifecycles.

Supply support for MAX31850EATB+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 and mixed-signal ICs for demanding industrial, medical, and communications applications - emphasizing integration, reliability, and low-power operation.

The MAX31850 series was developed specifically to simplify thermocouple-based temperature measurement by integrating cold-junction compensation, fault detection, and 1-Wire interface into a single compact IC - targeting distributed sensing in harsh, space-constrained environments.

FAQ

What thermocouple types does the MAX31850EATB+T support?

The MAX31850EATB+T is factory-calibrated exclusively for E-type thermocouples, with nominal sensitivity of 76.373 µV/°C and full-range operation from −270°C to +1000°C. It does not support K-, J-, N-, T-, R-, or S-type thermocouples - those require other variants such as MAX31850KATB+T or MAX31851RATB+T. Using a non-E-type thermocouple with MAX31850EATB+T will result in significant measurement error.

Can the MAX31850EATB+T operate without an external power supply?

Yes, the MAX31850EATB+T supports parasite-power mode, drawing operating energy from the 1-Wire bus via the DQ pin. In this mode, VDD must be connected to GND. However, during temperature conversion (72–100 ms), a strong external pullup (e.g., MOSFET-switched rail) is mandatory to supply peak current (~1.5 mA); weak pullups will cause communication failure or incomplete conversions.

How does the MAX31850EATB+T report thermocouple faults?

The MAX31850EATB+T reports thermocouple faults in bits 0–2 of scratchpad byte 2: bit 0 = open circuit, bit 1 = short to GND, bit 2 = short to VDD. When any fault occurs, bit 0 of the thermocouple temperature value (byte 0, MSb) also goes high - providing dual-flag confirmation. These flags persist until next conversion and require no host intervention to detect.

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

The AD0–AD3 pins on the MAX31850EATB+T provide hardware-programmable 4-bit location addresses (0–15), readable in the configuration register (scratchpad byte 4). This allows deterministic enumeration of up to 16 devices on the same 1-Wire bus without relying solely on 64-bit ROM IDs - simplifying firmware logic in fixed-topology systems like HVAC duct arrays or oven zones.

What is the maximum recommended ambient temperature for parasite-power operation of the MAX31850EATB+T?

Parasite-power operation of the MAX31850EATB+T is not recommended above +100°C ambient temperature due to increased leakage currents that can disrupt 1-Wire communication timing and reduce conversion reliability. For applications exceeding +100°C - such as furnace monitoring - use local VDD supply (3.0–3.7 V) to ensure robust operation across the full −40°C to +125°C rated range.