TSL235

t t D High-Resolution Conversion of Light Intensity to Frequency With No External Components D Communicates Directly With a Microcontroller D Compact Three-Leaded Clear-Plastic Package D Single-Supply Operation Down to 2.7 V D Nonlinearity Error Typically 0.2% at 100 kHz D Stable 100 ppm/°C Temperature Coefficient D Single-Supply Operation TSL235 LIGHTĆTOĆFREQUENCY CONVERTER SR PACKAGE (FRONT VIEW) TAOS003 – MAY 1999 1 23 Description GND VDD OUT The TSL235 light-to-frequency converter combines a silicon photodiode and a current-to-frequency converter on a single monolithic CMOS integrated circuit. The output is a square wave (50% duty cycle) with frequency directly proportional to light intensity. Because it is TTL compatible, the output allows direct interface to a microcontroller or other logic circuitry. The device has been temperature compensated for the ultravioletto-visible light range of 300 nm to 700 nm and responds over the light range of 300 nm to 1100 nm. The TSL235 is characterized for operation over the temperature range of –25°C to 70°C. Functional Block Diagram Light Photodiode Current-to-Frequency Converter Output Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted)† Supply voltage, VDD (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5 V Operating free-air temperature range, TA . . . . . . . . . . . . . . . . . . . . . . ....