The SI1145 is a new sensor from SiLabs with a calibrated UV sensing algorithm that can calculate UV Index.

• It's a digital sensor that works over I2C so just about any microcontroller can use it.
• individual visible and IR sensing elements so you can measure just about any kind of light - we only wrote our library to printout the 'counts' rather than the calculate the exact values of IR and Visible light so if you need precision Lux measurement check out the .
• If you're feeling really advanced, you can connect up an IR LED to the LED pin and use the basic proximity sensor capability that is in the SI1145 as well.
• Adafruit wrapped this nice little sensor up on a PCB with level shifting and regulation circuitry so you can safely use it with 3 or 5V microcontrollers.
• IR Sensor Spectrum: Wavelength: 550nm-1000nm (centered on 800)
• Visible Light Sensor Spectrum: Wavelength: 400nm-800nm (centered on 530)
• Voltage Supply: Power with 3-5VDC
• Output Type: I2C address 0x60 (7-bit)
• Operating Temperature: -40?C ~ 85?C

Each order comes with one fully assembled and tested PCB breakout and a small piece of header. You'll need to solder the header onto the PCB but it's fairly easy and takes only a few minutes even for a beginner. If you are using an Arduino, Adafruit have got a lovely already written up with example code so you can quickly read sensor readings and the UV index in under 10 minutes.