ams broadens smart lighting management offerings with standalone solution for color stability and lumen maintenance

ams, a leading worldwide supplier of high performance sensor solutions, introduced the AS7220 Smart Lighting Manager, which enables a new generation of higher-quality LED-based lamps and luminaires by using closed-loop sensing to maintain more accurate correlated color temperature (CCT) and lumen output while also lowering system bill of materials costs.

Following the launch in Jan 2017 of the AS7221 smart lighting manager that offered full white color tuning and daylighting features, the latest member of the ams Cognitive Lighting™ Smart Lighting Manager family, the AS7220 combines a precise calibrated-for-life color sensor with an intelligent Cognitive Lighting Engine for standalone closed-loop maintenance of  the output from strings of warmer and cooler white LEDs. The result is a luminaire which automatically adjusts for the color shift and lumen depreciation of LEDs as a natural result of aging, operating temperature changes and driver variation over lifetime.

In premium lighting systems marketed to commercial, industrial and high-end residential users, manufacturers must typically rely upon tightly-binned LED combinations to achieve the desired CCT. By employing sophisticated sensor-driven algorithms the ams AS7220 Smart Lighting 
Manager enables the manufacturer to use a more loosely CCT- and flux-binned range of cool-white and warm-white LEDs to achieve a high and stable quality of light. This gives them a substantial competitive advantage by:

broadening the competitive supply base from which LED production units may be sourced
increasing production flexibility and easing the management of LED inventory
easing the normal requirement for LED drivers and power supplies to provide precisely regulated outputs, loosening specifications and opening the supply base of those components

The AS7220 is easy to integrate into LED lighting system designs. After the desired CCT and/or full-output lumen values are programmed into it on the production line, it autonomously implements closed-loop color and output control of the LEDs inside a luminaire or lamp. Control of the power supplied to LED strings is implemented via either digital switching of multichannel power supplies, or through a combination of PWM current steering combined with an analog or digital output to standard single-channel 0-10V or PWM-input dimming ballasts or drivers.

“A continuing challenge in the LED lighting industry is to deliver precisely the same color and output not only over changes in operating temperature, but over the years of service life that customers expect”, said Tom Griffiths, Senior Marketing Manager at ams. While LEDs are well characterized for their first years of operation, longer term predictive models reveal variability in color and brightness. In addition, LEDs are evolving so fast that the same parts are unlikely to remain the cost-effective choice for the same model of luminaire even as little as one year after going into production, introducing still more variation from light to light.

“By adding closed-loop sensing to their product’s architecture, luminaire manufacturers free themselves from these technology and supply constraints, lowering bill-of-materials costs and gaining both consistency and a wider basis for component selection, while delivering more precise lighting quality over lifetime”, he said.

The AS7220 is pre-configured for optional operation with an external ams ambient light sensor to additionally provide for autonomous daylight harvesting using standard 0-10V dimming inputs. The Smart Lighting Manager also provides a direct interface to standard occupancy sensors to enable intelligent dimming control and energy-saving schemes.

Accurate and stable CCT control is enabled by the AS7220’s industry-first embedded tri-stimulus CIE XYZ color sensor, which directly maps the sensor channel data to the CIE 1931 color space. Nano-optic interference filters deposited on the die of AS7220 devices offer high stability and virtually no degradation over time and temperature. The sensor system’s LGA package, which measures just 4.7mm x 4.5mm x 2.5mm, includes a built-in aperture with a ±20.5° field of view. 
Using logic capabilities integrated into the device, the chip is able to deliver factory-calibrated CCT values typically accurate to within .002 du’v’ (approximately 2-3 Macadam steps) across its -40 to +85 degree C operating temperature range.

The AS7220 Smart Lighting Manager is available now in production volumes. Unit pricing is $2.81 in order quantities of 10,000 units. An evaluation kit for the AS722x family is available from the ams ICdirect online store. For sample requests and more technical information, go to www.ams.com/Smart-Lighting-Manager/AS7220.