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Connected lighting is one of the highest-growing segments of Internet of Things (IoT) applications, including residential and industrial lighting. High energy efficiency, low power consumption and safety are the most important factors for smart connected lighting innovation and energy saving. ON semiconductor provides a variety of low-power connection solutions such as Bluetooth Low Energy (BLE), Zigbee Green Power, and Power over Ethernet (PoE) to meet the connection needs of different lighting application scenarios, and its battery-free solution saves wiring or replacing batteries. To simplify and speed up design, ON Semiconductor will soon introduce a modular multi-connection, multi-sensor intelligent lighting platform for designers to use as a reference design for energy saving and innovation in building automation.

Smart Connected Lighting Market Trends and Enabling Technologies

After years of development, lighting technology continues to show new trends.

High energy efficiency is a constant theme. Since LED began to replace traditional light bulbs, it has taken a big step forward for lighting energy saving. But that’s not enough. Modern lighting technology needs to be able to dynamically adjust the lighting intensity according to the actual environment, such as determining the best lighting according to different natural light conditions and building lighting conditions. In addition, it is also necessary to adjust the lighting according to the state of the user. For example, in an office or a factory, the lighting system needs to decide how much lighting to provide to the corresponding area according to whether there is a user present. The lighting needs to be adjusted so that the light intensity of the entire place can transition evenly, otherwise the experience of other users will be affected.

In addition, modular design will be more popular, typical examples such as switches, dimmers and other devices are no longer fixed on the wall, but made into a small module, which can be moved and rearranged at will, as described later The battery-free switch that will be introduced.

Lighting can also be used to provide indoor positioning, such as using visible light communication, using the camera of a smartphone to perform indoor positioning of users, which has good application scenarios in supermarkets and shopping malls, enabling users to quickly find the goods and services they want, or It enables merchants to conduct in-depth analysis of user preferences through cloud big data.

From the control side, in addition to switch control, mobile APP control has also become popular. With the rise of intelligent voice, smart home devices, including electric lights, have begun to access intelligent voice control platforms, and users can use voice to adjust lighting. Some manufacturers have launched lighting systems that can learn automatically. After the user installs the lighting system for a period of time, the system can automatically adapt to the environment and determine the best lighting scheme according to the environment. The whole process does not require human intervention. In commercial scenarios, lighting has been sold as a service. Users do not need to worry about specific lighting equipment and the construction and installation process. They only need to pay for each unit of light, and the entire service is handed over to the supplier to complete.

In addition, there are some new applications, such as improving people’s work and rest through lighting, adjusting the biological clock, and agricultural lighting can supplement appropriate lighting when natural lighting is insufficient, thereby increasing crop yields.

All these applications require corresponding technologies such as modular design, more integrated smart home gateway, building/home automation control, artificial intelligence technology, BLE, PoE, power line communication (PLC), etc. Regardless of the technology used, the requirements for safety and low power consumption are common.

Connected Lighting Connection Requirements and Options

From a control standpoint, there are basic on/off, dimming, and color temperature controls. From the perspective of communication, Zhilian Lighting needs to have the ability of uplink communication and downlink communication, such as communication related to positioning, or the ability to connect to the background cloud service through the user’s mobile phone. From a service perspective, users expect manufacturers to help manage energy efficiency, adjust light intensity according to the usage environment, achieve automated control, integrate sensor networks, and make networking easier.

At present, the mainstream connection options in the market include BLE, Zigbee Green Power, PoE, etc. Both BLE Mesh and Zigbee are used in markets such as home/building automation, lighting, meter reading, and more. In terms of protocol application layer, BLE Mesh natively considers the interconnection of different devices. Zigbee 3.0 unifies the application layer development based on the cluster library (ZCL), and also launched the cross-platform IoT general development language Dotdot, which provides a wider range of IoT applications. The connection is ready. In terms of connecting to the cloud, BLE can be directly connected to mobile devices such as smartphones, and Zigbee needs to go through a gateway. In terms of routing, BLE Mesh adopts controlled flooding, while Zigbee adopts a routing algorithm based on path cost. Designers can choose the most suitable option based on application needs.

1. BLE mesh (Mesh) network

ON Semiconductor’s products for BLE, such as the Bluetooth 5 certified RSL10 series, use a unique design to achieve the industry’s lowest power consumption, power consumption in deep sleep mode is only 62.5 nanowatts (nW), and peak receive power consumption is only 7 milliwatts (mW). ).

The biggest advantage of BLE is that it is widely used in mobile applications and has a wide ecosystem. In addition, BLE is specially designed for low-power applications, supports energy harvesting, and conforms to the application trend of the Internet of Things (IoT), and BLE has supported Mesh networks since version 4.2, extending simple point-to-point communication into a many-to-many topology, thereby Provide a wider range of end-to-end communication, which meets the needs of networking in IoT applications. In theory, a Mesh network supports up to 32,000 nodes, communicates via broadcast, and has built-in secure network standards, enabling large-scale device networking where “many” devices communicate with “many other” devices. The ease of interoperability between different devices is another advantage of BLE, so it has become more and more widely used in commercial lighting, smart homes, building automation, IoT sensor networks, asset tracking and other fields in recent years.

In a typical BLE Mesh network, all nodes can send and receive information, and nodes in the network can have one or more functions, such as relay nodes to forward received information, and proxy nodes to enable Bluetooth low energy without Bluetooth Mesh stack. Devices can interact with nodes in the Mesh network, friend nodes store information about low-power nodes, and low-power nodes periodically poll friends for new information to save energy.

Extending the coverage of Mesh network is achieved through the forwarding mechanism of relay nodes. The BLE Mesh specification limits the number of message forwarding to no more than 126 times, and nodes that have already forwarded a message will not forward the same message again, thereby preventing network congestion while expanding network coverage.

BLE Mesh security is mandatory, all mesh messages are encrypted and authenticated. Security keys can be changed during the lifetime of the mesh network through a “key refresh” procedure. Scrambling makes it difficult to track messages sent within the network, thereby providing a privacy mechanism that makes it difficult to track nodes, enabling Mesh security to protect the network from replay attacks. In addition, the process of adding devices to a mesh network to become nodes is inherently a secure process. Nodes can also be safely removed from the network, preventing spam-scanning attacks.

2. Zigbee Green Power

ON Semiconductor’s chip for Zigbee 3.0 is NCS36510. Zigbee is based on IEEE 802.15.4 physical layer and MAC. It is a mature and secure connection standard. It has been supported by many smart lighting manufacturers, such as IKEA, Xiaomi, Philips, etc. Its new version is forward compatible. Zigbee is easy to implement in buildings, can be deployed and reconfigured flexibly, and can be connected over long distances using Mesh and a low-interference physical layer. Since Zigbee 3.0, the Zigbee protocol has launched a miniaturized Zigbee Green Power sub-protocol for low-power nodes such as battery-powered or battery-free energy harvesting solutions, which is in line with the general trend of energy saving and environmental protection.

battery-free technology

The battery-free technology is used in some smart connected lighting scenarios with as little maintenance as possible or maintenance-free, such as avoiding wiring and replacing batteries. The installation is simpler and more cost-effective. At the same time, it is portable, flexible, and easy to redeploy, which is in line with the general trend of environmental protection and energy saving. . ON Semiconductor’s energy harvesting switch solution is an example. It has a simple structure and can be installed on the existing switch panel, with flexible deployment, no construction and wiring, no additional DC-DC power supply, no battery, and long service life. The solution is mainly composed of the energy harvesting mechanical switch of Zeev and ON Semiconductor’s Zigbee system-on-chip (SoC) NCS36510. The energy harvesting mechanical switch is used to convert mechanical energy into electrical energy and store this electrical energy in a small capacitor. It is used in subsequent chips, and the protocol stack adopts DSR’s Zigbee Green Power. According to the different needs of customers, BLE can also be used for wireless communication in this solution.

3. PoE

In addition to wireless connections, PoE has also been used in lighting scenarios in recent years, because the latest 802.3bt power supply capacity has reached 90 W, which is enough to meet the requirements of residential lighting. The biggest advantages of PoE include cost advantages because the same cable can transmit both power and data, also supports daisy-chaining between light bulbs, in addition, wired communication is more secure and reliable than wireless communication, and Ethernet is available in most commercial buildings. Network interface, easy to deploy.

ON Semiconductor’s 60 W PoE Smart Connected Lighting Solution Uses Energy Harvesting Switches

In the wireless communication part of the battery-free solution, BLE RSL10 is used, which is especially suitable for ultra-low power consumption scenarios. In addition, the solution also uses 2 active bridges FDMQ8025A (built-in 4 MOSFETs), which meet the 802.3bt standard. Electrical device (PD) side interface controller IC NCP1095/96, DC-DC constant current step-down controller FL7760 supporting analog dimming and pulse width modulation (PWM) dimming, linear regulator NCP781 with input voltage up to 150 V (used to power the BLE chip on the receiving end).

Figure 1: ON Semiconductor’s 60 W PoE Smart Connected Lighting Solution

In this solution, the integrated controller compliant with IEEE802.3bt provides up to 60 W of power, and the energy efficiency reaches over 90%. The PWM dimming frequency is 1.3 MHz, and the PWM dimming duty cycle is 0 to 100%, which can achieve 1000 to 6000 lumens. Lighting intensity.

If designers want to change the power supply architecture, they can add isolated DC-DC to the platform, such as ON Semiconductor’s active clamp forward controller NCP1566, which supports two control modes: voltage mode and peak current control mode. Current, overvoltage, overpower protection and frequency synchronization functions, the energy efficiency of the entire system exceeds 92%.

Figure 2: Power over Ethernet-Powered Device (PoE-PD) Design Using DC-DC Converters

In particular, the PoE-level power conversion efficiency of this solution reaches 99.2%. The infrared thermal images of several main devices are shown in Figure 3. The test conditions are the 8th-level 71.3 W power at the PD end, and the lowest voltage and highest current input by the PD. At 41.1 VDC and 1.73 A, we can see that in a state of thermal equilibrium, the maximum temperature of the entire board does not exceed 53 °C without additional thermal treatment.

Figure 3: Infrared thermal image of the main device

Industrial Lighting Platform – Modular Design

The power of industrial lighting is often high, and in the case of AC power supply, power factor correction (PFC) is generally required. ON Semiconductor provides many high-performance PFC controllers for designers to choose. The environmental detection part, the control part of the mobile terminal, and the indoor positioning part are modularized and combined to form a complete intelligent lighting development platform.

Figure 4: The industrial lighting platform adopts a modular design

ON Semiconductor to launch modular LED lighting platform

The new platform supports BLE, Zigbee, PoE and other communication methods and AC input or PoE power supply, the output power range is 10 to 70 W, the lighting intensity is 1000 to 7000 lumens, and it supports uplink control such as on, off, dimming, programming, etc. And downlink operations such as positioning, LED light strings, ambient light, temperature/humidity sensors, etc. are all modular designs, which can be flexibly combined, and the energy efficiency exceeds 90%.

Lighting as a platform enables more innovation

From the market feedback, lighting is becoming a new platform, carrying more innovative applications. For example, in addition to installing light bulbs, lamps can also embed more and more sensors, including temperature, humidity, pressure and other environmental sensors, flight Time-of-Flight (ToF) sensors, gas sensors, etc. The application of large-area mesh networks is enabling innovative use cases such as indoor positioning, wayfinding and navigation, asset tracking, point-of-interest services, and more, further improving the ROI of connected lighting systems.

Summarize

Connected lighting is one of the fastest growing application categories in IoT, and the energy savings it brings provide a clear ROI. Connected Lighting is being transformed into a platform that supports multiple innovative use cases. ON Semiconductor’s low-power interconnected, battery-free energy harvesting solutions are driving innovation in Connected Lighting, and will launch a modular, multi-connected, multi-sensor connected lighting platform. Empower designers to achieve faster energy savings and innovation in building automation.