光感測

The JSA-1138 device, an ambient light sensor (ALS) with clear channel, features high sensitivity, wide dynamic range and fast communication speed through I2C interface. The JSA-1138 has 2 photodiodes. ALS PD is to sense visible light which includes 6 sensitive ranges and Clear PD is to sense visible and infrared which includes 2 sensitive ranges. The ALS/Clear reading (output count) is proportional to the illuminance regardless of the light sources; furthermore, no extra data manipulation is required. It also has a built-in circuit to reject the 50Hz/60Hz flicker noise caused by indoor light sources. Due to a well-engineered optical coating on the top of the ALS PD, its spectral response is almost the same as human eye's photopic vision. For Clear channel, the PD can sense visible and infrared light. So system can tell the external light source type by checking the Clear/ALS channel data, then different preset correction coefficient can be chosen to adapt to different light sources.