The TCS230 programmable color light-to-frequency converter combines configurable silicon photodiodes anda current-to-frequency converter on single monolithic CMOS integrated circuit. The output is a square wave(50% duty cycle) with frequency directly proportional to light intensity (irradiance). The full-scale outputfrequency can be scaled by one of three preset values via two control input pins. Digital inputs and digital outputallow direct interface to a microcontroller or other logic circuitry. Output enable (OE) places the output in thehigh-impedance state for multiple-unit sharing of a microcontroller input line.The light-to-frequency converter reads an 8 x 8 array of photodiodes. Sixteen photodiodes have blue filters, 16photodiodes have green filters, 16 photodiodes have red filters, and 16 photodiodes are clear with no filters.The four types (colors) of photodiodes are interdigitated to minimize the effect of non-uniformity of incidentirradiance. All 16 photodiodes of the same color are connected in parallel and which type of photodiode thedevice uses during operation is pin-selectable. Photodiodes are 120 µm x 120 µm in size and are on 144-µmcenters