Development challenges for ambient light sensor packages

Ambient light sensor (ALS) products are gaining popularity as one of the most effective solution for power management and display quality enhancement in electronic products and systems. The battery life for mobile phones, notebook computers, PDAs, and digital cameras can be extended significantly by automatic brightness control through ambient light sensor (ALS) feedback. A recent study shows that the display backlight represents one-third of the total battery drain in a notebook computer. It is also possible to achieve a more comfortable display quality with human eye-like sensing features. Automotive applications, room lighting, and advanced color sensing are other application areas for ALS that have been changing our daily life. Intersil has successfully developed ALS products with 5-, 6-, and 8-pin package configurations. A figure in the paper shows an example of an ALS product, EL7900, with a compact 5-pin QFN package format. EL7900 and ISL29000 are light-to-current optical sensors, integrating a photodiode and current amplifier for a simple current output sensor. Intersil has also developed light to digital output sensors in 8-pin packages, namely, ISL29001 and ISL29002, combining a photodiode, current amplifier, filter, ADC and an I²C output