Analog Devices Inc./Maxim Integrated MAX31850JATB+T

Overview

MAX31850JATB+T from Maxim Integrated is a cold-junction compensated, 1-Wire thermocouple-to-digital converter optimized for J-type thermocouples. It delivers 14-bit resolution (0.25°C), supports -210°C to +1200°C thermocouple range, achieves ±2°C accuracy from -210°C to +750°C, and operates from -40°C to +125°C ambient. It enables distributed temperature monitoring in industrial process control systems using parasitic or local power.

For engineers reviewing the MAX31850JATB+T datasheet, MAX31850JATB+T pinout, MAX31850JATB+T application, or MAX31850JATB+T equivalent, key selection considerations include J-type thermocouple support, 1-Wire multdrop capability, integrated cold-junction compensation, fault detection (open/short), and TDFN-EP package compatibility with space-constrained PCB layouts.

Technical Context

The MAX31850JATB+T integrates a precision 14-bit ADC, internal cold-junction temperature sensor, digital controller, and 1-Wire interface logic. Its signal path includes dedicated thermocouple input conditioning (T+/T−), programmable location address inputs (AD0–AD3), and fault-detection circuitry that identifies open circuits and shorts to VDD or GND.

It performs three synchronized operations during each conversion cycle: cold-junction temperature measurement, thermocouple voltage digitization, and real-time fault checking-all within a guaranteed 72–100ms conversion time. The device uses linear gain compensation (57.953 µV/°C nominal) calibrated specifically for J-type thermocouples, and stores results in a defined scratchpad memory map with CRC-protected data integrity.

Key Specifications

Pinout & Package

TDFN-EP (3mm × 4mm, 10-pin, exposed pad). Pin 10 (DNC) must remain unconnected; EP 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+, MAX31850JATB+T reduces wiring and MCU resource load via 1-Wire multdrop but trades off SPI speed and K-type flexibility. Against AD8495ARZ, it delivers full turnkey digital output with integrated diagnostics-eliminating design risk from external component tolerances and layout sensitivity.

Availability

MAX31850JATB+T is available at Aetrix Electronics and suitable for industrial process monitoring, HVAC system control, and appliance thermal safety requiring stable component supply across extended production lifecycles.

Supply support for MAX31850JATB+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.

The MAX31850 product line delivers integrated thermocouple interface solutions with embedded cold-junction compensation and 1-Wire connectivity-targeting distributed, low-wiring-cost temperature sensing in harsh environments.

FAQ

What thermocouple types does the MAX31850JATB+T support?

The MAX31850JATB+T is factory trimmed and calibrated exclusively for J-type thermocouples. Its analog front-end, gain coefficient (57.953 µV/°C), and internal compensation algorithms are optimized for J-type characteristics. It does not support K-, N-, T-, E-, R-, or S-type thermocouples - those require other variants such as MAX31850KATB+T or MAX31851SATB+T. Using a non-J thermocouple with MAX31850JATB+T will produce inaccurate readings.

Does the MAX31850JATB+T require an external power supply?

No - the MAX31850JATB+T supports parasite power via the DQ pin, eliminating the need for a local VDD supply. In parasite mode, VDD must be connected to GND, and a strong pullup (e.g., MOSFET-switched rail) is required during temperature conversions to sustain 1.5mA peak current. For continuous operation above +100°C or high-reliability applications, local VDD supply is recommended to avoid leakage-related communication failures.

How does the MAX31850JATB+T detect thermocouple faults?

The MAX31850JATB+T performs autonomous fault detection during every conversion cycle. It checks for open thermocouples and shorts to GND or VDD on the T+ and T− inputs using dedicated internal circuitry. Fault status is encoded in bits 0–2 of scratchpad byte 2: bit 0 = open circuit, bit 1 = short to GND, bit 2 = short to VDD. These flags appear alongside temperature data, enabling immediate system-level response without additional external components.

What is the purpose of the AD0–AD3 pins on the MAX31850JATB+T?

The AD0–AD3 pins on the MAX31850JATB+T provide hardware-programmable location addressing. Each pin can be tied to GND (logic 0) or DQ (logic 1) to assign a unique 4-bit address (0000–1111), allowing up to 16 physically distinct sensors to be mapped on the same 1-Wire bus. Their programmed values are readable in bits [3:0] of scratchpad byte 4, enabling firmware to correlate raw 64-bit ROM IDs with physical installation points without external EEPROM or manual configuration.

What is the maximum operating temperature range for the MAX31850JATB+T?

The MAX31850JATB+T is rated for an ambient operating temperature range of -40°C to +125°C. This specification applies to the IC's junction and package environment. While the J-type thermocouple itself supports up to +1200°C at the hot junction, the MAX31850JATB+T's accuracy and reliability are guaranteed only within its specified ambient range. Operation beyond +125°C ambient may cause parametric shift or communication failure, especially in parasite-power mode.