Hier steht es so beschrieben.

httpp://news.thomasnet.com/fullstory/26996

The TSL250RD, TSL251RD, TSL260RD and TSL261RD light-to-voltage converters each combine a photodiode and a transimpedance amplifier in a single monolithic IC. Their output voltage is directly proportional to the light intensity (irradiance) impinging on the photodiode. All four devices have improved amplifier offset-voltage stability and low-power consumption.

The TSL250RD has a high irradiance responsivity of 69 millivolts per microwatt per square centimeter and an output rise time of 260 microseconds. The less sensitive but faster TSL251RD has an irradiance responsivity of 17 millivolts per microwatt per square centimeter and an output rise time of 70 microseconds. The TSL250RD and TSL251RD light-to-voltage converters are packaged in clear plastic, which allows a response in the spectral range from 350 nanometers to 1000 nanometers.

The TSL260RD and TSL261RD are the infrared versions of the TSL250RD and TSL251RD devices, respectively. They are packaged in a visible light-blocking plastic, which cuts off the response below 700 nanometers.