RTD front-end in a single 20-SSOP package
The MAX31865AAP+T from Analog Devices is a complete RTD-to-digital converter that integrates a sigma-delta ADC, comparator, and register bank into a single 20-SSOP package. It converts the resistance of an external platinum RTD (Pt100 or Pt1000) directly to a digital reading over an SPI interface, with a guaranteed maximum accuracy of ±0.5°C across the full -40°C to 125°C operating range. This part is designed for industrial temperature sensing applications—motor drives, HVAC controllers, process transmitters, and battery-management systems—where a direct digital link to an MCU or FPGA is needed without external signal conditioning.
±0.5°C accuracy — what it means for the loop
The ±0.5°C maximum error includes the ADC, reference, and linearisation. The sigma-delta topology rejects line noise.
SPI interface — direct to the MCU bus
Communication is over a standard SPI bus, which means any microcontroller with a spare SPI port can read the conversion result directly from the on-chip register bank. No I²C address conflicts, no bit-banging a custom protocol. The 3V to 3.6V supply range lets it run from a 3.3V rail common on Cortex-M and FPGA boards. The register bank stores configuration, fault status, and the conversion result, so the host can poll or interrupt on threshold alarms—though this variant does not include a dedicated alarm output pin.
Active production, current-date-code supply
The MAX31865AAP+T carries an Active lifecycle status per the manufacturer and is ROHS3 compliant. No last-time-buy or end-of-life notices are active. This part is available through independent distribution in sealed reels with consistent date codes; we source and quote it to order against an RFQ.