Analog Devices Inc./Maxim Integrated MAX31850NATB+

Overview

MAX31850NATB+ from Maxim Integrated is a cold-junction compensated, 1-Wire thermocouple-to-digital converter optimized for N-type thermocouples. It delivers 14-bit resolution (0.25°C), supports -270°C to +1300°C measurement range, achieves ±2°C thermocouple accuracy from -200°C to +700°C, and integrates fault detection for open/shorted thermocouples - enabling direct replacement of analog signal chains in industrial temperature monitoring systems.

For engineers reviewing the MAX31850NATB+ datasheet, MAX31850NATB+ pinout, MAX31850NATB+ application, or MAX31850NATB+ equivalent, this page provides verified technical context, validated pin functions, confirmed N-type thermocouple calibration parameters, parasite-power timing constraints, and two production-validated alternative parts with documented functional differences.

Technical Context

The MAX31850NATB+ implements a dedicated 14-bit sigma-delta ADC with internal reference and programmable gain tailored for N-type thermocouple sensitivity (36.256 µV/°C). Its cold-junction compensation uses an on-die temperature sensor with ±2°C error over -40°C to +100°C, and stores both hot-junction and cold-junction values in separate 16-bit scratchpad registers.

It operates exclusively via 1-Wire interface (DQ pin), supporting parasite power mode requiring strong pullup during conversion (tCONV = 72–100 ms), and uses AD0–AD3 pins to encode location address into the configuration register - with no I²C, SPI, or UART interfaces present.

Key Specifications

Pinout & Package

TDFN-EP (3mm × 4mm, 10-pin, exposed pad); RoHS-compliant; EP may be connected to GND for thermal relief 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 MAX31855KASA+, the MAX31850NATB+ enables true 2-wire distributed sensing without added interface logic; compared with AD8495ARZ, it delivers complete digital output with built-in fault diagnostics and eliminates system-level calibration effort.

Availability

MAX31850NATB+ is available at Aetrix Electronics and suitable for industrial process monitoring, HVAC system control, medical sterilization equipment, and appliance thermal safety applications requiring stable component supply, long-term lifecycle support, and guaranteed authentic Maxim Integrated sourcing.

Supply support for MAX31850NATB+ 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 automotive applications, with emphasis on integration, reliability, and low-power operation.

The MAX31850 product line delivers cold-junction compensated thermocouple digitizers in 1-Wire format - engineered specifically for distributed, low-wiring-count temperature sensing in harsh environments where N-, K-, J-, T-, or E-type thermocouples are deployed.

FAQ

What thermocouple types does the MAX31850NATB+ support?

The MAX31850NATB+ is factory-trimmed exclusively for N-type thermocouples, with calibration optimized for 36.256 µV/°C nominal sensitivity and validated error performance across -270°C to +1300°C. It does not support K-, J-, T-, E-, R-, or S-type thermocouples - those require other variants such as MAX31850KATB+ or MAX31851RATB+. Using non-N-type thermocouples with MAX31850NATB+ yields uncorrected measurement errors exceeding ±10°C.

Can the MAX31850NATB+ operate without an external power supply?

Yes, the MAX31850NATB+ supports parasite power mode, drawing operating current from the 1-Wire bus via the DQ pin. In this mode, VDD must be connected to GND, and a strong MOSFET-based pullup must be activated during the full 72–100 ms conversion period. Parasite power is not recommended above +100°C due to increased leakage current that can disrupt bus communication - for high-temperature use, local VDD supply is required.

How does the MAX31850NATB+ detect thermocouple faults?

The MAX31850NATB+ performs hardware-level fault detection during each conversion cycle, reporting results in scratchpad byte 2 bits [2:0]. Bit 0 = high indicates open thermocouple; bit 1 = high indicates short to GND; bit 2 = high indicates short to VDD. These flags appear simultaneously with temperature data and require no additional command - the host reads byte 2 alongside bytes 0–1 to obtain both measurement and health status in one transaction.

What is the function of the AD0–AD3 pins on the MAX31850NATB+?

The AD0–AD3 pins on the MAX31850NATB+ are hardwired location address inputs that encode a 4-bit binary value (0000 to 1111) into the device's configuration register (scratchpad byte 4). This allows up to 16 uniquely addressable MAX31850NATB+ units to share the same 1-Wire bus without ROM-search overhead - the master reads the config register to identify physical location instead of performing time-consuming 64-bit ROM searches for each device.

Does the MAX31850NATB+ require external components for basic operation?

Yes, the MAX31850NATB+ requires a 4.7 kΩ weak pullup resistor on the DQ line for standard 1-Wire signaling, and a MOSFET-based strong pullup circuit (e.g., 2N7002 with 3.3 V gate drive) activated during temperature conversion. No external reference, amplifier, or cold-junction sensor is needed - all compensation and digitization are integrated. The exposed pad (EP) should be connected to GND for optimal thermal performance but is not electrically required.