LM75A I2C Temperature Sensor Module — High Precision Digital Output
The LM75A temperature sensor module delivers 11-bit digital temperature readings over I2C with a resolution of 0.125°C across a -55°C to +125°C range. The chip includes a configurable over-temperature alert output that triggers when the measured temperature exceeds a set threshold — useful for fan control or shutdown circuits without polling the bus. Up to eight LM75A modules share one I2C bus by setting three address pins, covering multi-zone temperature monitoring without extra wiring complexity.
- 0.125°C resolution — 11-bit ADC, finer than the DHT11 (1°C) or DS18B20 (0.0625°C comparable)
- -55°C to +125°C range — suitable for outdoor and industrial temperature ranges
- I2C / SMBus interface — works at 2.8V to 5.5V supply
- Configurable alert output — open-drain, triggers at a user-set over-temperature threshold
- Up to 8 devices on one bus — address pins A0, A1, A2 set the 7-bit address
| Specification | Value |
|---|---|
| Sensor IC | LM75A |
| Temperature range | -55°C to +125°C |
| Resolution | 0.125°C (11-bit) |
| Accuracy | ±2°C (-25°C to +100°C) |
| Interface | I2C / SMBus (400kHz fast mode) |
| Supply voltage | 2.8V – 5.5V |
| Default I2C address | 0x48 |
| Alert output | Open-drain, configurable hysteresis |
How do you read the LM75A temperature on Arduino?
Connect SDA and SCL to the Arduino’s I2C pins (A4/A5 on Uno), supply 3.3V or 5V, and use the Wire library to read two bytes from register 0x00. The temperature in Celsius is the 16-bit result divided by 256. Several ready-made libraries including LM75 by QuentinCG are available in the Arduino Library Manager and reduce setup to three lines of code.
Can the alert pin replace a temperature polling loop?
Yes. Set the over-temperature threshold register (OS register) and the hysteresis register (Hyst register) via I2C, then connect the alert pin to an Arduino interrupt pin. The interrupt fires when temperature crosses the threshold, eliminating the need to poll the sensor in a loop and freeing up CPU time.
Best for
Arduino temperature monitoring, Raspberry Pi enclosure thermal management, 3D printer hotend ambient sensing, server rack temperature alerts, multi-zone temperature logging, battery charge temperature protection, and ESP32 smart home climate sensors.
Why Kunkune
Shipped from UK stock with Royal Mail. 60-day returns, no minimum order. Buy one or a handful for multi-zone projects.
Buying in bulk? For orders of 10+ units or trade pricing, contact us for a custom quote.
