The MAX31865 is an easy-to-use resistance to digital converter optimized for platinum resistance temperature detectors (RTDs).

An external resistor sets the sensitivity of the RTD being used, and a precision delta-sigma ADC converts the ratio between the RTD resistance and the reference resistance into digital form.

The MAX31865's inputs are protected against surge failures up to Q45V. Programmable RTD detection and open and short wire conditions are included.

• Operating voltage: 5V (with a 3.3V regulator and level switch); Supports RTD platinum resistance from 100Ω to 1kΩ (0℃) (PT100 to PT1000) (module resistor uses 430R).
• MAX31865 RTD PT100 Platinum Resistance Temperature Detector Module. Resistance temperature detectors (RTD) are temperature sensors that contain a resistor that changes its resistance value as the temperature changes, essentially a type of thermistor.
• We even made compatible the 5V breakout, with a 3.3V dimmer and level changer, compatible with 2, 3 and 4 wire sensor ports, SPI compatible interface. so you can use it with any microcontroller.
• The resistance is 100 ohms at 0°C. Compared to most NTC/PTC thermistors, PT-type RTDs are much more stable and accurate (but also more expensive). PT100 Its accuracy, repeatability and stability are very high.
• If you want to achieve this kind of accuracy and accuracy, you should use an amplifier designed for low-resistance measurements. The best option is an amplifier that automatically adjusts and compensates for the resistance of the connecting wire.

• Integration reduces system cost, simplifies design efforts and reduces design cycle time:
  
  • Simple conversion of RTD resistor from platinum to digital value
  • Handles platinum RTD from 100 Ω to 1 kΩ (at 0°C) (PT100 to PT1000)
  • Compatible with 2, 3 and 4 wire sensor connections
  • SPI compatible interface
• High accuracy makes it easy to meet error budgets:
  
  • 15-bit ADC resolution; Rated temperature resolution 0.03125 NC (varies due to non-linearity of RTD)
  • Total accuracy in all operating conditions: 0.5 NC (0.05% of full scale) max.
  • Fully differential VREF inputs
  • Conversion time of 21 ms (max)
• Built-in fault detection increases system reliability:
  
  • ±45V input protection
  • Fault detection (open RTD element, RTD in short circuit to out-of-range voltage or short circuit between RTD elements)

1. Datasheet - BMT MAX31865 PT100 SENSOR AMP