Other micro-controller uses 5v as standard input voltage, many latest device modules, popular sensors, GPS, RF modules, Flash Memories, SPI storage, Display, use 3 to 3.3v most of this devices requires logic level conversion to protect them from high voltage
This is the Silicon Labs Si7021 i2C Humidity / Temperature Sensor. Si7021 is a monolithic CMOS IC that integrates humidity / temperature sensor elements this device has an analog to digital converter, signal processing, calibration data, and an i2C interface.
This Is an Infrared thermometer a non-contact temperature measurement sensor develop by Melexis microelectronics integrated system, code name MLX90614. The MLX90614 has thermopile detector chip and the signal conditioning ASSP are integrated in a low noise amplifier, 17 bit ADS