MAX31865

RTD-to-Digital Converter

Complete Solution Provides a Digital Temperature Reading from an RTD with Fault Detection and Input Voltage Protection


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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 ±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

MAX31865: Block Diagram MAX31865: Block Diagram Enlarge+

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 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)

Applications/Uses

  • Industrial Equipment
  • Instrumentation
  • Medical Equipment
Part NumberSensor TypeFunctionsInterfaceChannelsAccuracy
(±°C)
Parasite Pwr.Temp. Resolution
(bits)
Oper. Temp.
(°C)
Package/PinsBudgetary
Price
See Notes
MAX31865 Remote
RTD-to-Digital Converter
Thermistor-to-Digital Converter
SPIOne0.5No15-40 to +125
SSOP/20
THIN QFN/20
$3.00 @1k
See All Temperature Sensors (113)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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