General Description

The MAX31865 is an easy-to-use resistance-to-digital converter optimized for platinum resistance temperature detectors (RTDs). An external resistor sets the sensitivity for the RTD being used and a precision delta-sigma ADC converts the ratio of the RTD resistance to the reference resistance into digital form. The MAX31865’s inputs are protected against overvoltage faults as large as ±50V. Programmable detection of RTD and cable open and short conditions is included.

Features

Simple Conversion of Platinum RTD Resistance to Digital Value

Handles 100Ωto 1kΩ(at 0°C) Platinum RTDs (PT100 to PT1000)

Compatible with 2-, 3-, and 4-wire Sensor Connections

Conversion Time: 21ms max

15-Bit ADC Resolution; Nominal Temperature  Resolution 0.03125NC (Varies Due to RTD Nonlinearity)

Total Accuracy Over All Operating Conditions: 0.5NC (0.05% of Full Scale) max

±50V Input Protection

Fully Differential VREFInputs

Fault Detection (Open RTD Element, RTD Shorted to Out-of-Range Voltage, or Short Across RTD Element)

SPI-Compatible Interface

20-Pin TQFN Package