STMicroelectronics, a semiconductor leader serving customers across the spectrum of electronics applications, has introduced a complete and configurable solution to develop and efficiently control a dimmable, high-brightness LED string (up to 100W) for street-lighting applications. Based on ST’s award-winning STLUX385A digital power controller, the street-lighting plug-and-play design highlights the device’s ability to optimize LED efficiency at any dimming level and minimize power in idle conditions.
Replacing incandescent, low-pressure sodium and high-intensity discharge streetlights with LEDs is widely seen as the most promising way to reduce the huge amount of energy that the world uses to light the streets of its cities, towns and villages. LEDs are inherently more efficient than earlier lamp technologies and, more important, they are dimmable. This means that, in conjunction with a smart power supply, their light output can be rapidly adjusted to scenarios ranging from ambient daylight to bright moonlight. In addition, they can also implement civic policies such as dimming selected lamps at a chosen time.
Many cities around the world have started to convert their existing streetlamps to use LED technology and even more are drawing up plans to do so. In the USA, for example, Boston, Massachusetts had converted 40% of its 64,000 electric streetlamps to LEDs by the end of 2012 and was already realizing $2.8 million savings annually in electricity costs, about 35% of that expense.
“Digitally controlled lighting is the key to saving energy in outdoor installations,” said Matteo Lo Presti, Group Vice President and General Manager, Industrial and Power Conversion Division, STMicroelectronics. “ST’s new solution for LED street lighting packs 25 years of experience in power conversion into a single, future-proof platform; as grids get progressively smarter, cities will be able to control the streetlamps to produce even greater savings because all the key communications protocols are already incorporated in the STLUX385A.”
The reference design includes full schematics, bill of materials and firmware, enabling customers to rapidly develop digital power controllers for 100W LED lamps using ST’s unique STLUX385A, the world’s first universal digital controller for lighting and power-conversion applications. In this solution, the STLUX385A device handles a primary-side regulated power-conversion stage, as well as all the supported communication links. The power-conversion stage consists of a PFC regulator followed by a Zero Voltage Switching (ZVS) LC-resonant stage. High-precision dimming is controlled using a primary-side regulation (PSR) control technique.
The demonstration board provides all the key physical-communication interfaces such as DALI (Digital Addressable Lighting Interface), insulated 0-10 and UART, with all the communication managed by the STLUX385A device. The flexibility of the STLUX385A also allows the board to be easily connected to other interfaces such as Wi-Fi, power-line modems, Bluetooth® and ZigBee®.
The demonstration board is available now at $140 with order code STEVAL385LEDPSR.