What is a MCP9808 sensor ?

The MCP9808 is a high-accuracy digital temperature sensor with an I²C interface, designed by Microchip Technology. 

Highly precise, programmable, and with low power consumption, it is ideal for industrial applications, medical devices, and embedded electronic systems requiring fine temperature monitoring (Arduino, ESP32, Raspberry Pi, etc.). 

Its operation is based on an integrated bandgap temperature sensor and a 13-bit analog-to-digital conversion (ADC), providing the temperature directly in the form of digital data with a typical accuracy of ±0.25 °C.

Operating principle

The MCP9808 measures internal temperature using a bandgap reference whose voltage varies linearly with temperature (highly stable principle, less sensitive to drifts than a simple diode). 

This voltage is converted by a ΔΣ (Delta-Sigma) converter into a digital value, transmitted via the I²C bus.

T(°C) = Binary code x 0,0625 

Each increment (LSB) represents 0.0625 °C (in default resolution mode). The unit communicates on the I²C bus according to the master/slave protocol, with up to 8 selectable addresses (0x18 to 0x1F).

Temperature curve / numerical value (13-bit resolution)

💡 Each LSB = 0.0625 °C, with a configurable resolution (0.5 / 0.25 / 0.125 / 0.0625 °C) for fine accuracy.

Principle diagram (I²C connection)

     +3.3V
       │
      [MCP9808]
       │ SDA ───────── A0/A1/A2 (address selection)
       │ SCL ─────────┤── [I²C Microcontroller]
       │ ALERT (option)
       │ GND ─────────┘

💡 The MCP9808 supports up to 8 sensors on the same I²C bus thanks to its 3 address-selection pins (A0, A1, A2).

Application areas

🌡️ High-precision thermal monitoring of industrial systems

🧠 Embedded IoT, smart sensors, and connected gateways

🔋 Server room cooling, UPS, laptops

🧪 Medical instrumentation, laboratory devices, and DAQ systems