LCD Thermometer TCN77 Using AVR Microcontroller


The TC77 is a digital temperature sensor with a Serial Peripheral Interface. Temperature data is converted from the internal thermal sensing element and made available at anytime as a 13-bit two’s compliment digital word. Communication with the TC77 is accomplished via a SPI and MICROWIRE compatible interface. It has a 12-bit plus sign temperature resolution of 0.0625°C per Least Significant Bit (LSb). The TC77 offers a temperature accuracy of ±1.0°C (max.) over the temperature range of +25°C to +65°C. When operating, the TC77 consumes only 250 ìA (typ.). The TC77’s Configuration register can be used to activate the low power Shutdown mode, which has a current consumption of only 0.1 uA (typ.).
LCD Thermometer TCN77


  • Digital Temperature Sensing in 5-Pin SOT-23A and 8-Pin SOIC Packages
  • Outputs Temperature as a 13-Bit Digital Word
  • SPI and MICROWIRE™ Compatible Interface
  • Solid State Temperature Sensing
  • ±1°C (max.) accuracy from +25°C to +65°C
  • ±2°C (max.) accuracy from -40°C to +85°C
  • ±3°C (max.) accuracy from -55°C to +125°C
  • 2.7V to 5.5V Operating Range
  • Low Power – 250 uA (typ.) Continuous Conversion Mode – 0.1 uA (typ.) Shutdown Mode


The TCN77 is available in a SOIC package.

LCD Thermometer TCN77LCD Thermometer TCN77_1


Serial Bus Interface

The serial interface consists of the Chip Select (CS),Serial Clock (SCK) and Serial Data (SI/O) signals. The TC77 meets the SPI and MICROWIRE bus specifications,with the serial interface designed to be compatible with the Microchip PICmicro® family of microcontrollers.The CS input is used to select the TC77 when multiple devices are connected to the serial clock and data lines. The CS line is also used to synchronize the data, which is written to, or read from, the device when CS is equal to a logic ‘0’ voltage. The SCK input is disabled when CS is a logic ‘1’. The falling edge of the CS line initiates communication, while the rising edge of CS completes the communication. The SCK input is provided by the external microcontroller and is used to synchronize the data on the SI/O line.The Temperature and Manufacturer ID registers are read only while the Configuration register is a read/write register.

Temperature Data Format

A 13-bit two’s complement digital word is used to represent the temperature. The Least Significant Bit (LSb)is equal to 0.0625°C. Note that the last two LSb bits (Bit 0 and 1) are tri-stated and are represented as a logic ‘1’ in the table. Bit 2 is set to logic ‘1’ after the completion of the first temperature conversion following a power up or voltage reset event.

For more details, click:LCD Thermometer TCN77 Using AVR Microcontroller


About The Author

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough research and presenting information in a structured and logical format.

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