A bright future for efficient, connected lighting
This demand for improved efficiency and more functions is being met by smart, or connected, lighting control. The market for smart control of lighting in residential applications is four times larger in volume than in industrial buildings. Together, they are the fastest-growing segment of the Internet of Things (IoT). Generally, residential connected or connected lighting systems tend to be much simpler than their industrial counterparts, with a smaller Bill of Materials (BoM) and lower cost.
At its simplest level, connected lighting can just be the ability to turn lights on and off, perhaps remotely or at pre-programmed times of the day. Taking this one step further, connected lighting systems can add extra features such as dimming and color control of LEDs.
Beyond this, there is a huge range of options available, particularly when sensors are added to the mix – for example, to control lighting in response to the level of ambient light, or whether people are detected in a room. For industrial applications, sensors such as temperature, moisture and lighting levels can be invaluable, as their data can be used both to control the lights, and to help with system maintenance.
Today’s ubiquitous smartphones means that lighting systems can offer a sophisticated user interface on a mobile device, without the cost of a dedicated screen or complicated buttons.
Connecting it all together
Of course, one of the most important aspects of a smart lighting system is how everything communicates, and the connectivity technology used. The requirements for connectivity include when we are commissioning the system, the links between each device in use, and communication between the building management system and our controlled lighting.
The first decision is whether we want a wired or wireless connection. For battery-powered lights, wireless has the key benefit of not requiring any running or routing of cabling, which can deliver significant cost savings. Popular wireless protocols used for lighting include Bluetooth Low Energy and Zigbee Green Power, while Near Field Communications (NFC) may be used for setup and commissioning.
For mains powered lights, wireless can still be a good option, as it avoids the need for a second, data cable to run alongside the power cabling. Alternatively, Power over Ethernet (PoE) means it is now possible to use a single cable for both power and connectivity.
Power over Ethernet for lighting systems
The PoE 2 standard (802.3bt) can provide up to 90 W of power – plenty for an LED-based light, with its lower power consumption compared to traditional incandescent bulbs.
An example of this in practice is a 60 W connected lighting solution that is powered via its Ethernet cable, using an IEEE 802.3bt compliant integrated controller. Capable of supporting up to two LED strings, the solution has two LED channels that incorporate the FL7760 high-side sensing, constant current Buck controller from ON Semiconductor.
With this arrangement the PWM signal can control dimming from 0-100%, using a PWM frequency of 1.3 MHz. The brightness control is provided by a Bluetooth Low Energy radio such as the RSL10 that is suitable for use in RF enabled harvesting solutions. The supply voltage for the RSL10 is provided by a simple high voltage LDO.
This solution achieves efficiencies of greater than 90%, ensuring that almost all the energy derived from the PoE controller is converted into light, allowing the design to deliver up to 6000 Lumen. Such performance is well-aligned to the prevailing pressure to minimize power demands and deliver connected lighting solutions.
Bluetooth Low Energy mesh networking
Instead of straightforward point-to-point communications, wireless mesh technology is ideally suited to industrial lighting applications, as it allows a large number of devices to connect with each other as well as externally. Bluetooth Low Energy now incorporates the ability to create a mesh network of up to 32,000 devices with inbuilt security as standard, vastly simplifying the setup of extended range lighting solutions.
functions to support the mesh framework (Source: Bluetooth SIG(
Within the mesh, each node can act as a light while having one or more other functions, each of which are essential to the functionality of the overall mesh framework. Relay nodes can re-transmit received messages thereby extending the network almost infinitely if necessary. Proxy nodes communicate with others that are not Bluetooth Low Energy or Bluetooth Low Energy-capable, bringing them into the mesh, while ‘friend’ nodes store messages for other nodes that are operating in low power mode. Low power nodes periodically poll the friend nodes for messages, thereby saving more energy.
Security is essential in any connected system and Bluetooth Low Energy mesh networks are no exception. All messages are encrypted / authenticated and obfuscation makes tracking messages difficult, thereby protecting against replay attacks. Within the Bluetooth Low Energy protocol, there is a process to change security keys and another secure process to add nodes to the mesh. When nodes are removed from a Bluetooth Low Energy network, this is also done securely to prevent ‘trashcan’ attacks.
Zigbee protocols.
An alternate approach to Bluetooth Low Energy mesh networking is Zigbee Green Power, which has been established longer. Zigbee is built on top of IEEE 802.15.4 MAC and PHY, and features in lighting products such as those from Ikea, Xiaomi and Philips, among others. The eco-friendly and low power protocol is compatible with new building trends and is easy to implement in buildings, deploy and reconfigure.
While Bluetooth Low Energy (now) has a native mesh model and uses a smartphone for cloud connectivity, Zigbee relies on Dotdot or a Zigbee cluster library (ZCL) and has a dedicated gateway as few, if any, mobile devices are Zigbee-capable.
Zigbee can make use of battery-free or energy harvesting technology to deliver light switches that are portable, eco-friendly and maintenance-free. As there is no wiring required, they can be placed almost anywhere and installation is very inexpensive.
Setting-up an energy harvesting switch using devices such as ON Semiconductor’s NCS36510 can be achieved quickly and easily. The low power, fully integrated, System on Chip offers advanced power management and an IEEE 802.15.4 compliant transceiver. It supports the design of a complete and secure wireless network with minimal external components.
Connected lighting Platform
To make development simpler and quicker, ON Semiconductor has created a modular development kit for industrial LED lighting solutions. This Connected Lighting Platform includes a connectivity module built around the RSL10 System in Package (RSL10 SIP), which enables controls such as on/off, dimming and programming.
The RSL10 FOTA mobile app is available on Google Play and Apple’s app store, and adds support for wireless firmware upgrades. The RSL10 Sense and Control app enables developers to control and monitor environmental sensors and actuators from a mobile device. Adding new functions, and further customization, is supported by use cases provided in a CMSIS pack.
The Connected Lighting Platform supports up to two LED strings. Its LED driver board has two FL7760 drivers, one for each LED string, delivering up to 70 W per string. Overall, the system can provide up to 70 Watts, delivering up to 7000 Lumen, and more if selecting a higher efficiency LED (150 Lumen / Watt for example). A choice of power modules means the platform can be powered from either an AC/DC power supply or using PoE.
Flexibility and control
Even if a system is relatively simple, connected lighting can deliver the key benefit of reduced energy usage, and hence lower costs. This is making it an obvious choice for many use cases in both industrial and residential environments. And as connected lighting grows in capabilities, we are seeing new applications open up, such as medical therapy and agriculture.
For every one of these areas, there’s a need for an optimized control system, that keeps the Bill of Materials cost low, and balances sophisticated features with simplicity. By using a design kit with an EMS-friendly BoM such as the ON Connected Lighting Platform, developers can save valuable time in building their LED lighting systems, and reduce risk – whatever the application.
About the author:
Bruno Damien is IoT Strategic Marketing Director EMEA at ON Semiconductor – www.onsemi.com
If you enjoyed this article, you will like the following ones: don't miss them by subscribing to :
