Product Introduction
| The MAX31865 is an easy-to-use thermistor-to-digital converter optimized for platinum resistance temperature detectors (RTDs). An external resistor sets the RTD sensitivity, and a high-precision delta-sigma ADC converts the ratio of the RTD resistance to a reference resistor into a digital output. The MAX31865 inputs are protected against overvoltages up to ±45V, and provide configurable detection of RTD and cable open and short conditions. When it comes to accurate temperature sensing, nothing beats a platinum RTD. Resistive temperature detectors (RTDs) are temperature sensors that contain a resistor that changes resistance as temperature changes, essentially a thermistor. In this sensor, the resistor is actually a platinum strip that has a resistance of 100 ohms at 0°C, hence the name PT100. RTD-type PTDs are more stable and accurate (but also more expensive) than most NTC/PTC thermistors. The PT100 has been used for temperature measurement in labs and industrial processes for many years and has gained a good reputation for accuracy (better than thermocouples), repeatability, and stability. However, to get precision and accuracy out of a PT100 RTD, you must use an amplifier designed to read low resistances. Even better, there is an amplifier that automatically adjusts and compensates for the resistance of the connecting wires. If you are looking for a great RTD sensor, the MAX31865 is designed to work with any 2, 3, or 4-wire PT100 RTD! We carry a variety of MAXIM thermocouple amplifiers, and the MAX31865 can handle all of your RTD needs and can even compensate for 3 or 4-wire RTDs for increased accuracy. Connect to any microcontroller via SPI and read the resistance ratio on the internal ADC. We place a 430Ω 0.1% resistor as a reference resistor at the breakout. We have some example code that will calculate the temperature based on your resistance. |
Product Features
Features and Benefits
1. Supports 100Ω to 1kΩ (at 0°C) platinum resistance RTD (PT100 to PT1000);
2. Compatible with 2-wire, 3-wire and 4-wire sensor connections;
3. SPI compatible interface;
4. 15-bit ADC resolution, nominal temperature resolution is 0.03125°C (varies with RTD nonlinearity);
5. Total accuracy remains at 0.5°C (0.05% full scale) under all operating conditions;
6 Fully differential VREF input;
7. Conversion time: 21ms (maximum);
8. Integrated fault detection to increase system stability: (RTD open circuit, RTD short circuit to voltage outside the range or RTD element short circuit).
Product Photos
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