Maxim Integrated Products introduces the MAX9635, a fully integrated digital ambient-light sensor (ALS) with a unique adaptive gain block. Designed using the company's proprietary BiCMOS technology, this device integrates two photodiodes, an ADC, and all necessary digital functionality into a tiny 2mm x 2mm package.

This integrated solution saves valuable space in tight enclosures while delivering the industry's highest performance. The MAX9635 consumes 100x less power than the nearest competitive product, significantly extending battery life. Additionally, it offers an industry-best 4,000,000 to 1 dynamic range to ensure ultra-precise lux readings in all ambient-light conditions.

The MAX9635 is ideally suited for tablet and notebook PCs, smartphones, TVs, digital lighting-management systems, and light-intensity monitoring applications.

Ambient-light sensors are increasingly used in a variety of display and lighting applications to save power and improve the user experience. With ALS solutions, system designers can automatically adjust display brightness based on the amount of ambient light. Since backlighting accounts for a significant portion of the system's power budget, dynamic brightness control can translate into substantial power savings.

Replicating the optical response of the human eye with electronic components is difficult. Traditional light sensors measure the amount of light in an environment regardless of wavelength. These designs are unduly influenced by ultraviolet and infrared light, which are not perceptible by the human eye. This leads to inaccurate ambient-light readings and, therefore, widely varying brightness adjustments. This problem is only exacerbated by the fact that light sources can have different spectra; for instance, incandescent light has more infrared content than fluorescent light.

Maxim's BiCMOS technology enables the integration of two photodiodes along with an optical filter to reject ultraviolet and infrared light. This allows the MAX9635 to replicate the optical response of the human eye and accurately measure visible light in a variety of environmental settings. Advanced algorithms correct for any spectra variations between light sources, ensuring an extremely accurate lux response.

Ambient-light sensors require the widest dynamic range possible to support a broad spectrum of light conditions, from direct sunlight to complete darkness with every variation in between. Even in digital light sensors, the gain has to be set to a certain value to address different modes of operation in multiple light scenarios. This added configuration requirement increases both design complexity and time to market.

The MAX9635 is uniquely equipped with an adaptive gain block that automatically selects the optimum gain range. This capability relieves designers of the time-consuming process of manually programming the device. Additionally, the adaptive gain block provides the industry's widest dynamic range (more than 4,000,000 to 1), enabling the MAX9635 to measure light levels from 0.045 lux to 188,000 lux. Simply stated, this innovation delivers the most precise lux measurements over the widest range of ambient-light conditions.

As an added benefit, the device's low-light sensitivity makes it suitable for applications in which the sensor IC is placed behind black glass, which greatly reduces the amount of ambient light.

The MAX9635 is designed to meet the tightest of power budgets. The device's minuscule 0.65microamp operating current is lower than the power-down current of many competitive products, and it operates from an industry-low 1.7V to 3.6V supply voltage. Consuming as little as 1.1microwatts of operating power, the MAX9635 uses 100x less power than the nearest competitor (124microwatts).