An integrated smart lighting and connectivity solution

High-efficiency and easy-to-manage smart lighting solution

Smart buildings are based on an intelligent network system that enables communication and interaction between IoT devices. Through the Internet, remote sensing, control, and automation programming of various electronic devices in residential and commercial buildings can be achieved. For example, homeowners can use their smartphones, tablets, or personal computers to activate the security system, control temperature, turn on/off appliances, adjust lighting, set up a home theater, or operate other entertainment systems while on vacation.

The implementation of smart buildings requires meeting certain basic requirements. The devices should possess a certain level of intelligence, be interconnected and connected to the cloud. They should have the ability to derive new applications from their primary functions (e.g., using speakers for playing alerts), and they should allow for the addition of new devices, applications, and services on top of the existing infrastructure.

Whether for residential, commercial, or industrial purposes, buildings require internal lighting. Today, lighting systems in buildings have the potential to be efficient and energy-saving. Traditional incandescent and halogen bulbs have been largely replaced by LED lighting. However, the power supply and usage methods of lighting have not changed significantly. The conventional approach to installing lighting involves laying power cables to the intended luminaire locations. However, the mains power supply is AC (alternating current), whereas LEDs require DC (direct current) power. This necessitates the use of a transformer to rectify the AC power and often an additional DC-DC converter to down-convert the rectified DC output from the transformer.

Imagine if it were possible to route DC power directly to the luminaires and consider utilizing the luminaires for more than just providing lighting to individual rooms. In fact, luminaires can offer a range of different functionalities beyond illumination. For instance, by adding sensors for temperature, humidity, and imaging to the lighting devices, it becomes possible to monitor room temperature, humidity levels, and occupancy. By adding wired or wireless connectivity to these solutions, end-users can track all relevant information in the cloud and make real-time adjustments, thereby enhancing efficiency, comfort, and security. All these devices are interconnected and can be managed to ensure optimal operation of the smart building. Additionally, considering how individual luminaires can be interconnected and integrated into a lighting system, automation of lighting can be achieved within the building management system.

However, to achieve the aforementioned functionalities, it is necessary to address the challenges of providing the DC power required for sensors and reliable digital connectivity to the luminaires. Wireless technologies can be ruled out due to the extensive use of insulation materials and thick walls in energy-efficient buildings. Power over Ethernet (PoE) is a promising solution as modern smart buildings typically have Cat5 or Cat6 Ethernet cables already installed as a standard configuration. Routing Ethernet cables to the luminaires instead of main power cables can provide both connectivity (at the selected speeds) and power delivery (using PoE) to the sensors and the luminaires.

Visible Light Communication (VLC) addresses indoor positioning and data transmission challenges

On the other hand, VLC technology enables functionalities such as indoor positioning and data transmission. As the name suggests, VLC utilizes light instead of radio frequency (RF) for communication. Data is converted into modulated light and transmitted to the receiver. The modulated light is captured by an image sensor or a photodiode at the receiver end and converted into a digital signal, which is then processed by the system's microcontroller.

In fact, VLC is not a new technology and dates back to the 1880s. However, due to factors such as inadequate stability of light sources, VLC technology did not see significant development. The latest advancements in LED technology have revived the applicability and efficiency of VLC. The new LED technology makes it easier to use the same LED for both illumination and communication, eliminating the need for separate communication infrastructure. VLC does not require the installation and deployment of dedicated communication nodes, access points, or beacons. Instead, it can be integrated into existing luminaries.

Using visible light as a data carrier offers significant advantages, as information access points or broadcast points can be integrated into existing lighting infrastructure, thereby saving installation costs and complexity. By employing modulation techniques that do not require deep modulation depths and maintaining a stable average luminance level, the expected illumination level for users can be preserved. By operating at modulation frequencies above several kHz, the data stream remains completely invisible to the human eye.

Of course, optical communication will never replace radio frequency (RF) communication. It is a complementary technology that can coexist and even collaborate in many use cases to achieve the best results in applications. One of the primary applications of VLC is indoor positioning systems in industrial environments, where the technology is used to identify the location of assets such as packages or forklifts. By embedding a unique identifier in each LED driver, indicating the position within a building, the LED driver emits signals through visible light to the receiver. The receiver can calculate the position by detecting the codes, and it can be a sensor camera module or a photodiode.

In its simplest form, the mobile unit can have a pre-programmed floor plan. The floor plan database contains unique IDs and the positions of the luminaires, which continuously transmit their unique IDs. An optical sensor or camera module on the mobile unit can capture the IDs, and through an application, triangulation can be performed to determine the position of the mobile unit. This allows for on-site accuracy in the range of 10 to 15 centimeters in all three dimensions.

Providing a one-stop solution for luminaire designers

Currently, there are various types of connected luminaires available on the market. However, most of the existing solutions typically use a separate LED driver IC and a PoE controller for data connectivity. An innovative solution provided by onsemi is the NCL31010, which integrates both devices into a single package, making individual luminaires an integral part of a fully interconnected and manageable lighting system with the capability to perform many other functions.

The NCL31010 device can deliver over 90W of power through PoE and includes two auxiliary DC-DC converters to power the microcontroller and sensors. One of the key innovations of this device is its application in VLC, which cannot be achieved with traditional lighting systems that require separate LED drivers and PoE controllers. This involves directly modulating (invisible) data onto the LED lights, enabling them to act as positioning beacons for indoor positioning systems such as Yellow Dot™, overcoming the significant accuracy limitations of other wireless systems (e.g., GPS, Wi-Fi™) in indoor positioning applications.

By implementing PoE as the power and connectivity solution, the functionality of LED luminaires goes beyond simple illumination of the building interior. This enables the luminaires to support a range of other intelligent features, facilitating the realization of building automation. The NCL31010 serves as a one-stop-shop solution for luminaire designers, providing comprehensive management of their power and connectivity requirements.

Highly integrated and multifunctional LED driver

The NCL31010 is a PoE-enabled LED driver that integrates all the necessary elements for connecting and managing a lighting system, including VLC (50kHz bandwidth) and indoor positioning capabilities. It is certified to comply with the IEEE802.3bt/at/af standards and can deliver over 90W of system power.

The NCL31010 features a highly efficient buck LED driver (97%) that supports high-bandwidth analog and PWM dimming down to zero current. It includes two auxiliary DC-DC converters for powering the system microcontroller and sensors, offering high-accuracy measurements (±1%) and diagnostics for monitoring input and output current and voltage, LED or system temperature, as well as DC-DC voltage and current. The NCL31010 also integrates a 3.3V buck converter that can be adjusted from 2.5V to 24V and supports either I²C or SPI serial interfaces.

The NCL31000 series includes the non-PoE version, NCL31000, to accommodate other communication standards, and the reduced feature version, NCL31001, which supports multi-channel solutions. The NCL31000 series finds applications in interconnected LED lighting, visible light communication, indoor positioning, and common end products include smart LED luminaires, managed LED lighting systems, and multi-channel LED lighting, among others.

Conclusion

Smart lighting serves as a foundation in smart building applications, and when combined with PoE and VLC technologies, it can significantly reduce deployment costs and open doors to many new applications, overcoming some limitations of RF technology implementation today. With highly integrated and efficient LED drivers from onsemi, valuable additional technologies for expanded information and positioning services can be provided, making it an ideal solution for smart lighting applications.