RTD-to-Digital Converter

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 ±45V. Programmable detection of RTD and cable open and short conditions is included.

Applications

* Industrial Equipment

* Instrumentation

* Medical Equipment

* 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

* High Accuracy Facilitates Meeting Error Budgets

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

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

* Fully Differential VREF Inputs

* 21ms (max) Conversion Time

* 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)