The TSL237S released by Texas Advanced Optoelectronic Solutions Inc. (Taos) is a high-resolution light-to-frequency converter that combines a silicon photodiode and a current-to-frequency converter on a single monolithic CMOS integrated circuit. Output is a square wave -- 50% duty cycle -- with frequency directly proportional to the light intensity, or irradiance, on the photodiode. The instrument is temperature-compensated for the UV to the visible range, from 320 to 700 nm, and it responds from 320 to 1050 nm. Digital output enables direct interface to a microcontroller, and operating temperature ranges from –25 to 70 °C. The converter comes in a three-lead clear plastic side-looker package with an integral lens.