The TSL230, TSL230A, and TSL230B programmable light-to-frequency converters combine a configurable silicon photodiode and a current-to-frequency converter on single monolithic CMOS integrated circuits. The output can be either a pulse train or a square wave (50% duty cycle) with frequency directly proportional to light intensity. The sensitivity of the devices is selectable in three ranges, providing two decades of adjustment. The full-scale output frequency can be scaled by one of four preset values. All inputs and the output are TTL compatible, allowing direct two-way communication with a microcontroller for programming and output interface. An output enable (OE) is provided that places the output in the high-impedance state for multiple-unit sharing of a microcontroller input line. The devices are available with absolute-output-frequency tolerances of 5% (TSL230B), 10% (TSL230A), or 20% (TSL230). Each circuit has been temperature compensated for the ultraviolet-to-visible-light range of 300 nm to 700 nm. The devices are characterized for operation over the temperature range of 25C to 70C.