The EM1820/EM1821 is an ALS-only chip for measuring the intensity of visible light as seen by the human eye. The EM1820/EM1821 is available in an ultra-small APK6 Flip package with a package size of 0.97mm x 0.886mm x 0.22mm, making it suitable for applications in small spaces. The EM1820/EM1821 have a fixed addressing scheme that allows the device to operate with only four pins connected. This allows PCB designers to create larger openings for the active sensor area.
The EM1820/EM1821 have strong infrared (IR) suppression to measure the intensity of light as seen by the human eye, and the sensor's precise spectral response matches that of the human eye regardless of the light source. IR rejection also helps maintain high accuracy when the design requires the sensor to be mounted under dark glass. The EM1820/EM1821 are typically used in conjunction with a backlight IC or lighting control system to create a light-based experience for humans, replacing photodiodes, photoresistors or lower-performance ambient light sensors.
The EM1820/EM1821 has a built-in full scale setting function that allows measurement in the range of 0.0005lux to 50k lux without having to manually select the full scale range. This feature allows light measurements to be made over a 16-bit effective dynamic range. The digital operation is flexible and allows for easy system integration. Measurements can be made continuously or in a single pass. The digital signal is output via a two-wire serial interface via I2C.
