Digital controller is customized for intelligent lighting applications

February 11, 2013 // By Christoph Hammerschmidt
Greener, more economical and safer lighting systems is what chipmaker STMicroelectronics promises to users of its STLUX385 programmable digital controller. The company claims that this is the first such product specifically optimized for lighting and power-supply applications and simplifies the design of traditional power-conversion topologies for lighting applications. The STLUX385 is addressing the domestic, commercial and public lighting systems market.

The key to the new possibilities for improving the performance of LED, fluorescent and HID (High-Intensity Discharge) lighting systems is the STLUX385's combination of a proven, cost-effective STM8 microprocessor core and a unique set of peripherals aimed at simplifying the design of the lighting power supply and digital control of the lights. Depending on factors such as the lighting technology used, the input power source (AC or DC), dimming requirements and safety or reliability issues, many different types of power conversion and control topologies are required in the current and emerging lighting applications and the STLUX385 is - according to STMicroelectronics - the first device able to address all of these via a single programmable chip. 

“More than 20% of the electricity generated is used to light our homes, streets, offices, factories and public areas, and making lighting more efficient is an essential step on the path towards a sustainable world,” said Matteo Lo Presti, STMicroelectronics Group Vice President, Industrial & Power Conversion Division.

The STLUX385 achieves this goal primarily by integrating six specially-designed peripherals called SMED (State Machine, Event-Driven) circuits that interact with each other and with external signals via a programmable switching matrix to control the power delivered to the lighting elements. In addition to the specific application signals, the SMEDs can process external commands to turn the lights on/off or set the dimming level, diagnostic signals such as open- or short-circuit detected, or inputs from sensors in applications where the lighting is designed to adapt to ambient conditions. 

Image: STLUX385 block diagram. For better resolution click here .

For example, this opens the way towards intelligent LED street lamps that increase their brightness gradually as daylight fades and, conversely, automatically reduce their brightness as the sun rises instead of having only a full brightness or off-setting at predetermined times.
The product also allows sophisticated lighting systems that currently require the use of expensive external DSPs.