Osram's Digital Sensor Combines Proximity and Ambient Light Sensors

The digital SFH 7770 sensor replaces the usual separateambient light and proximity sensors. It measures 2.8 x 2.8 x 0.9 mm and by combiningthe two functions, it offers added performance and consumes 350 AmuA during operationand only 5 AmuA in stand-by mode.

The proximity sensor uses the reflectionof the emitted light from a separate IR LED to detect objects close to it and torecognize whether the object is moving toward or away from it. Its high sensitivityin the range from 1 AmuW/cmA 2 to 10 mW/cmA 2 allows it to operate at long distances ofup to 30 cm. With its digital output, the sensor supports the high-speed IA 2C busat up to 3.4 MHz.

When it measures brightness, the integratedambient light sensor immediately returns a lux value of between 3 and 65,000 lxso that the display brightness can be adapted precisely to the ambient light conditions.This makes the display easier to read and increases the time between battery recharges.The sensor is not influenced by the 50-60 Hz fluctuations in the brightness of ambientlight produced, for example, by fluorescent lamps.

The digital double pack of proximity andambient light sensor gives manufacturers of cell phones new freedom of design. Differentfunctionalities can be achieved with just one component - depending on the phone,it could be only the proximity function, only the ambient light function, or bothtogether. The board design and the number of manufacturing processes are the samein all cases.

By using two further IR LEDs, it is possibleto detect gestures with the SFH 7770. Thenecessary hardware drivers are already integrated. The IR LEDs transmit light signalsat a certain frequency. The sensor measures the reflections to detect horizontaland vertical movements. Gesture detection from such small components makes contactlesscontrol of applications possible even for very small cell phones and smart phones.Users can flick through photos without even touching the phone or disable an integratedtouchpad to prevent starting an app unintentionally.

Osram's Digital Sensor Combines Proximity and Ambient Light Sensors