Maxim Integrated Distributor

MAX31865 RTD-to-Digital Converter


Maxim Integrated’s single-chip, RTD-to-Digital converter reduces costs by 50%


Maxim Integrated's MAX31865 RTD-to-Digital Converter (click for full-size)The Maxim 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, and a precision delta-sigma ADC converts the ratio of the RTD resistance to the reference resistance into digital form. The MAX31865 inputs resist overvoltage faults as large as ±50 V. Programmable detection of RTD open, cable open, and short conditions is included.

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 overvoltages, 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
  • Simple conversion of platinum RTD resistance to digital value
  • Handles 100 Ω to 1 kΩ (at 0°C) platinum RTDs (PT100 to PT1000)
  • Compatible with 2-, 3-, and 4-wire sensor connections
  • Conversion time: 21 ms max
  • 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
  • ±50 V input protection
  • Fully differential VREF inputs
  • Fault detection (open RTD element, RTD shorted to out-of-range voltage, or short across RTD element)
  • SPI-compatible interface
  • 20-pin TQFN package

Digi-Key P/N Manufacturer P/N Description  
MAX31865ATP+-ND MAX31865ATP+ IC RTD TO DIGITAL CONVERT 20QFN Datasheet
MAX31865EVKIT#-ND MAX31865EVKIT# BOARD EVAL FOR MAX31865 Datasheet