The Adafruit PCT2075 Temperature Sensor is a precise, affordable I2C temperature sensor and a drop-in replacement for the classic LM75. With an 11-bit ADC (compared to the LM75's 9-bit), it delivers finer temperature resolution. Three-state address pins allow up to 27 sensors on a single I2C bus — over three times the LM75's limit of 8.

The PCT2075 measures ambient temperature and includes a configurable high-temperature threshold alert. When the current reading exceeds the set threshold, an interrupt output is raised. Additional registers let you adjust alerting behaviour and measurement timing. STEMMA QT connectors make wiring solderless and simple.

Key Features

• 11-bit Temperature ADC – Higher resolution than the 9-bit LM75 it replaces
• I2C Interface – Code-compatible with LM75; drop-in upgrade
• Up to 27 Sensors per Bus – Three-state address pins (high, low, floating)
• Over-Temperature Alert – Configurable threshold with interrupt output
• STEMMA QT / Qwiic – Solderless STEMMA QT connectors for easy daisy-chaining
• Breadboard Friendly – Standard 0.1″ header pinout

Ideal For

• Ambient temperature monitoring in electronics projects
• Upgrading existing LM75-based designs with better resolution
• Multi-sensor temperature arrays (up to 27 on one bus)
• Over-temperature alert and shutdown systems

Resources

• PCT2075 Learn Guide (schematics, pinouts, libraries, datasheets)