Description

The MAX31865 is an easy-to-use resistance-to-digital converter optimized for platinum resistance temperature
detectors (RTDs).The MAX31865 simply and elegantly solves the common industrial design problem of digitizing a platinum RTD (such as a PT100 or PT1000) resistance, protects against ±50 V input over-voltages, and detects sensor and cable faults. In addition, the device simplifies resistance measurement by eliminating the precisely matched current sources used for 3-wire sensor connections in conventional designs. The built-in overvoltage protection (OVP) also eliminates the need for external protection circuitry, which lowers cost, reduces board space, and increases factory uptime.

Features of MAX31865 Converter:
1.Integration Lowers System Cost, Simplifies Design
Efforts, and Reduces Design Cycle Time->
•Simple Conversion of Platinum RTD Resistance to
Digital Value
•Handles 100Ω to 1kΩ (at 0°C) Platinum RTDs
(PT100 to PT1000)
•Compatible with 2-, 3-, and 4-Wire Sensor Connections
•SPI-Compatible Interface
•20-Pin TQFN and SSOP Packages

2.High Accuracy Facilitates Meeting Error Budgets->
•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
•Fully Differential VREF Inputs
•21ms (max) Conversion Time

3. Integrated Fault Detection Increases System
Reliability->
•±45V Input Protection
•Fault Detection (Open RTD Element, RTD Shorted to
Out-of-Range Voltage, or Short Across RTD Element)