Intelligent LED street light and building lighting communication, control and protection solutions

1 Introduction

Smart Lighting involves communication and sensing functions that enable remote control (turning on or off, dimming or changing colors) and monitoring (remote diagnostics) of one or more fixtures in a building, street or home. Intelligent lighting also provides information to the luminaire so that it can be adjusted for brightness depending on usage or ambient light. On the other hand, high-brightness white LEDs are ideal for area lighting applications, with better directionality, better color quality, and environmental protection, and can be more easily controlled to turn on and off, allowing automatic detection of ambient light to change brightness. It is gaining more and more attention in applications such as smart LED street lights.

Intelligent lighting communication can be achieved with wireless or existing power line infrastructure. The power line is the world's largest copper infrastructure, with power outlets in every corner of the home or office building, making it an extremely wide-ranging network.

Since all lighting fixtures are connected to the power line to convert electricity into light, power line communication (PLC) has become a reasonable way to communicate the main communication and control links of intelligent lighting.

Using its advanced semiconductor technology, ON Semiconductor has introduced communications, sensors, KNX transceivers and protection solutions for intelligent lighting that help perform the same (or even more) tasks with less power, further improving energy efficiency and saving energy.

For example, using ON Semiconductor's PLC modems (such as AMIS-49587), PLC line drivers (such as the NCS5650), and ambient light sensors such as the NOA1302, it is easy to build a networked LED street light intelligent control system based on power lines, which helps municipalities, Power companies and commercial enterprises remotely adjust the light output of street lights to reduce the overall energy consumption of their street light networks. In addition, in building intelligent temperature regulation and lighting control applications, KNX transceivers can also be used on twisted pair cabling for lighting control with KNX networks.

Figure 1 Overview of the modem, power supply and sensor solutions for intelligent LED street lights by ON Semiconductor

2 PLC modems that meet market standards and meet strict international standards

Power line communications help utility companies add a higher level of functionality to their distribution networks, allowing consumers to better manage their own energy consumption. ON Semiconductor offers a range of leading spread-spectrum frequency shift keying (S-FSK) PLC modems such as AMIS30585, AMIS49587 and NCN49597. Among them, AMIS-30585 and AMIS-49587 are based on ARM7 core microcontroller (MCU), only support AC work, the maximum baud rate per channel is 1.2k and 2.4k respectively; the new NCN49597 is based on ARM Cortex M0 core MCU, It also supports AC and DC operation, with a maximum baud rate of 4.8k per channel, supports CenelecA, B, C and D bands, and provides programmable software. It is also expected that the NCN49599 PLC modem with integrated power amplifier function based on NCN49597 will be launched in the second half of 2012.

These rugged, narrowband PLC modems embed PHY+MAC, comply with strict international standards (FCC, CENELEC, IEC61334-5-1) and operate on low and medium voltage networks to provide the best bill of materials (BOM) cost and Very low energy consumption.

3 KNX Transceiver and Evaluation Board

KNX is an open architecture interconnect (OSI)-based network communication protocol that complies with intelligent building standards. KNX is a combination of the previous three standards, including the European Home System Protocol (EHS), BatiBUS and the European Installation Bus (EIB or Instabus). The open standards supported by KNX include: EN50090 European Standard, ISO/IEC14543-3 International Standard, GB/Z 20965 Chinese Standard, ANSI/ASHRAE135 American Standard.

The KNX transceivers from ON Semiconductor include the NCN5120, NCN5121, NCN5110, and NCN5111, which can be used to connect appliances and sensors to provide temperature and light control for the 9600 baud KNX twisted pair (TP) bus in a building. The twisted pair bus provides data communication and power supply.

Table 1 ON Semiconductor KNX Transceiver

Figure 2 KNX network communication architecture

It is worth mentioning that ON Semiconductor and NXP Semiconductors recently jointly launched an evaluation board and a complete reference design for energy-efficient twisted pair networks. This evaluation board uses NXP's low-power Cortex-M0 microcontroller LPC1227 and ON Semiconductor's NCN5120 receiver-transmitter IC to help building automation customers simplify the design process and apply the energy-efficient KNX twisted pair solution. For applications such as lighting switches and controls, HVAC control, blinds and occupancy detection.

4 Motion Detector Passive Infrared Controller (PIR) ON Semiconductor's NCS36000 passive infrared controller is used in the lighting and occupancy sensing market to amplify and adjust the signal from the PIR sensor. The device operates from 3.0V to 5.75V and integrates a low noise 2-stage amplifier with an internal reference voltage to drive the sensor; an internal oscillator with an external RC; single or dual pulse detection; digital filter for maximum Limit false alarms; drive LEDs and relays directly. The device is a very flexible solution, allowing customers to customize digital filtering and analog processing for a wide range of sensors, with lower BOM cost than comparable discrete solutions.

5 Ambient light and distance sensor

Ambient light sensors are also important components for building intelligent lighting. ON Semiconductor's ambient light sensor has design flexibility, can be adjusted in the EEPROM as needed, custom filter 0.0125 lx detection (ie, clear light response); in addition, with dark current and temperature compensation, minimum per bit resolution power consumption; The high-speed mode I2C interface does not affect the bus operation when the power is turned off.

Figure 3 NOA1302 ambient light sensor

6 LED string protection scheme

The preferred method of driving the LEDs is to connect the LEDs in series so that the currents in the LED strings match to the same brightness. Although LEDs are very reliable, if any of the LEDs fail open, the entire string of LEDs will go out because the LED strings are connected in series, which is unacceptable for high-reliability applications such as street lighting. To solve this problem, the NUD4700 can be used to bridge each LED. This shunt bypass protector ensures that the rest of the LED string is always lit when an LED fails open. The NUD4700 features high on-state current capability and low-off-state leakage, and can be automatically reset to off if the LED is restored; the repeatable response time is short. Its high reliability helps extend the life of LED strings and luminaires, enabling LED strings to operate at high currents, making them suitable for high-reliability applications such as streetlights, tunnel lighting, architectural lighting, high ceiling lighting, and train and runway lights. .

7 High-brightness LED module ESD protection

Sensitive HB LED dies are susceptible to harmful electrostatic discharge (ESD) during assembly and end user operations. In addition, HB LED modules are susceptible to high voltage ESD during lamp and luminaire assembly and can cause damage.

Figure 4 Protecting the LED string with the NUD4700

ON Semiconductor offers die-level ESD protection products that can be used in conjunction with HB LEDs in optical hoods. In-module silicon transient voltage suppressor (TVS) dies provide the protection needed to eliminate faults and help create rugged HB LED modules for a variety of applications. There are two types of silicon TVS die in the module: sub-mounted protectors and side-mounted dies. For example, the CM1771 is a 100V back-to-back electrostatic discharge (ESD) protection device with a proprietary side-mounted construction that withstands high levels of ESD strikes, and has a small footprint and low height. Protect the HB LED die and HB LED modules during assembly and luminaire assembly to prevent malfunctions.

8 Summary

In order to achieve energy conservation and environmental protection, government agencies, power companies or commercial enterprises are striving to build a networked LED street light intelligent control system or intelligent building control system, using the ambient light/distance sensor integrated in the system, according to the brightness and occupancy of ambient light. Information such as the situation to automatically adjust the light output of the LED. ON Semiconductor's advanced communications, sensors, KNX transceivers and protection solutions help reduce the total energy and cost of the lighting network for a powerful and environmentally friendly LED lighting system.

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