RTD-to-Digital Converter

Description

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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.

Design Solution: Achieve High-Accuracy Temperature Measurement in Your Precision Designs ›

How to Measure Temperature Using RTDs and the MAX31865EVKIT

Key Features

• 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 V_REF 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)

Applications/Uses

• Industrial Equipment
• Instrumentation
• Medical Equipment