Light-to-Voltage Optical Sensor - The TSL254R is a precision CMOS Light-to-Voltage sensor that combines a photodiode and a transimpedance amplifier on a single monolithic IC. The feedback resistor is 1 Megohm. The output voltage is directly proportional to the light intensity(irradiance) on the photodiode. At 635nm, the irradiance responsivity is 9mV/(uW/cm2) with an output rise and fall time of 2usec.