Maxim enters the optical sensor market with the industry's highest performance ambient-light sensor

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


Ambient-light sensing saves battery life and improves display performance
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.

Accurate measurement of visible light
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.

Industry's only adaptive-gain technology provides the widest lux measurement range
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.

MAX9635 cuts power consumption by 100x

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).

The MAX9635 is the only light sensor in the industry that can operate from 1.8V, allowing it to be powered by the same 1.8V supply as the I2C interface. This helps reduce power consumption and lowers complexity by only requiring a single voltage rail for the part. An address pin allows the use of two sensors on the same I2C bus.

A built-in interrupt function extends these power savings by reducing the frequency of I2C communications. With this technique, the light sensor only initiates communication with the microcontroller when the ambient-light measurement exceeds the programmed threshold. This eliminates the need to constantly poll the sensor, thus offloading the processor and conserving power.