Date: 31/03/2009

Ambient light sensor ICs for LCD display backlighting from Rohm

ROHM Semiconductor has announced a new family of analog and digital Ambient Light Sensor (ALS) ICs for control of LED backlighting for LCD-equipped devices. Rohm says, the spectral response of ROHM ALS ICs closely match human eye for accurate light measurement. These devices sense different ambient light sources from incandescent or fluorescent light to full sunlight.

Advantages and features of ROHM ALS Series include:
Higher light-sensing accuracy (Rohm claims ±15% compared to its competitive devices that range from ±30% to ±55%)
Stable ambient light detection (Rohm claims ±10% maximum difference regardless of light source, compared to competitive products with up to 4:1 variations)
Operating temperature range of -40°C to 85°C
Light detection range up to 100,000 lux
RoHS-compliant and halogen-free package

The ROHM ALS IC family includes the BH16xx (analog) / BH17xx (digital) series. BH16xx analog series devices provide a linear current output proportional to luminous intensity ranging from 0 to 100,000 lux. These ICs provide three-level gain selection matching power consumption to the specific application requirements.

The BH17xx series of digital devices integrate a 16-bit analog-to-digital converter that produces 1 lx resolution over a range of 0 to 65,000 lx. The devices' I2C output is designed for direct connection to a microcontroller or baseband processor. Two measurement resolution levels are provided allowing design trade-offs between sampling time and performance. For example, with high-resolution sampling, optical noise such as fluorescent lamp flicker can be filtered out. Low resolution provides a shorter sampling time for applications such as GPS systems where the light level changes are dynamic.

Steve Chutka, Field Applications Engineer at ROHM, said: "Adjusting the LED backlight intensity to compensate for varying light levels can save 50% or more of the total power required to operate many LCD-equipped devices. The ROHM family of analog and digital ALS ICs offers an exceptional range of performance capabilities for the full gamut of LED backlighting applications."

ROHM Semiconductor's analog and digital ALS ICs are available in either the ultra-small WSOF5 surface-mount package (1.6x1.6x0.55 mm) or the slightly larger WSOF6 surface-mount package (3.0x1.6x0.7 mm).

Fore more information visit: www.rohmsemiconductor.com/als.html