Tiny ambient light sensors
By using the TSL2520/21 to maximize the viewable screen area, smartphone manufacturers can provide the best possible user experience while enabling effective camera image correction.
The ams TSL2520 is an ambient light sensor (ALS) which features four photodiodes for visible light sensing and two infrared photodiodes, a combination which allows for rejection of IR interference and produces very accurate measurements of ambient light intensity (lux).
The photodiodes are placed at the end of the sensor’s 2mm x 1mm x 0.5mm package which means that the device can be positioned at the gap between the display screen and the chassis of the phone to maximize the screen-to-body ratio.
The TSL2521 provides the same ALS function and the identical mechanical specifications as the TSL2520 but also offers flicker detection capability. Sensing flicker in artificial light sources such as LEDs at frequencies up to 7kHz, the TSL2521 provides an image correction input to the phone’s camera. This enables the camera to eliminate banding and other flicker-generated artefacts that can distort captured images and videos.
The sensors’ accuracy and high sensitivity, measuring ambient light levels down to just 1mlux, support responsive display brightness management and help improve camera image quality.
Adding to the design flexibility which ams optical sensors afford, the TSL2520/21 products feature programmable gain which gives a dynamic range of 8192x. This means that the sensors can operate under any glass types and inks with any degree of light attenuation without requiring a visible aperture in the display glass.
The sensors operate from a 1.8V supply and feature configurable sleep modes.