The TSL235R light-to-frequency converter outputs a square wave (50% duty cycle) with frequency directly proportional to light intensity (irradiance).
The device has been temperature compensated for the ultraviolet-to-visible light range of 320 nm to 700 nm and responds over the light range of 320 nm to 1050 nm.

The TSL235R can be powered at anywhere between 2.7 and 5.5V, and will typically pull about 2mA of current. It comes in a simple, 3-pin through hole package.
No external components are necessary to use the converter, and the digital output allows direct interface to a microcontroller or other logic circuitry.

Features:

• High-resolution conversion of light intensity to frequency with no external components
• Communicates directly with a microcontroller
• Compact three-leaded clear-plastic package
• Single-supply operation down to 2.7 V
• Nonlinearity error typically 0.2% at 100kHz
• Stable 150 ppm/°C temperature coefficient
• Single-supply operation

Documents:

• Datasheet