As people's awareness of energy conservation and environmental protection is increasing, the industry is paying more and more attention to the impact of energy consumption on the environment. Among various energy consumption pathways, it is estimated that up to 20% to 22% of electrical energy is used for illumination. Increasing the energy efficiency of lighting applications and even further reducing their energy consumption will help reduce carbon dioxide emissions and create a greener world. Therefore, energy-efficient lighting is becoming a focus of competition in the industry. From the application field, lighting covers different categories such as residential lighting, industrial lighting, street lighting and restaurant, retail and service lighting. In terms of power level, in addition to low-power lighting, it also includes high-power area lighting. Typical applications such as bollards, wall wash, wall pack, tunnel lighting, street lights, parking Outdoor lighting for field and public security lighting, industrial and retail lighting, and indoor lighting for low bay, high bay, freezer/refrigerator and parking garage. There are many challenges in high-power area lighting, such as the possibility that the luminaire may be difficult to access, the safety problem may occur when the light source fails, and there are many extreme environmental conditions in the outdoor. In addition, it is worth noting that existing light sources (such as metal halide lamps (MHL), high pressure sodium lamps (HPS), linear fluorescent lamps (LFL), and compact fluorescent lamps (CFL)) are used in high-power area lighting. There are many limitations, such as the poor color rendering of high-pressure sodium lamps (CRI is about 22), the typical lamp loss of metal halide lamps is higher (40%) and the time from start-up to illumination to full brightness may take up to 10 minutes. Linear fluorescent lamps have poor cold temperature performance, and compact fluorescent lamps also have slower startup speeds. On the other hand, as high-brightness white light-emitting diodes (LEDs) continue to improve in terms of performance and cost, they are increasingly used for high-power area lighting and offer advantages not found in traditional light sources, such as emitting light per lumen. It consumes less power, has better direction control, better color quality, is environmentally friendly, and can be more easily controlled by turning it on and off, allowing automatic detection of ambient light to change brightness; in addition, LED reliability is better. Helps reduce maintenance costs and total cost of ownership. LED area lighting application requirements The main function of the LED driver is to flow at a lower limit of various conditions and to protect the LED from surges and other fault conditions, as well as to provide a level of safety against vibration and ignition (electrical and/or mechanical). For regional lighting applications, outdoor environments present temperature challenges to LED drivers and may require AC input voltages higher than the standard voltage of 277 Vac, 347 Vac, or even 480 Vac. LED drivers for regional lighting applications may also need to meet certain regulatory standards for power factor or harmonic content. For example, the European Union's International Electrotechnical Union (IEC) IEC61000-3-2 standard requires harmonic content of lighting devices (class C) with a power exceeding 25 W, equivalent to a total harmonic distortion (THD) of less than 35%; However, compliance with IEC61000-3-2 Class C harmonic content requirements does not necessarily mean that the power factor (PF) is higher than 0.9. In some markets (such as the US), PF is generally required to be above 0.9 and THD is below 20%. Many regional lighting applications are outdoors and may withstand a variety of stringent temperature conditions, which can affect overall service life. While the overall system design has a significant impact on service life, it is important to use an energy-efficient LED driver with less internal heat and lower losses, and to thermally isolate the driver from the LED heat source in the design to enhance system reliability. Figure 1: Smart Dual Brightness Level LED Street Lighting Example The control of LED lighting can also become more intelligent. Traditional street lights come from the main control with a timer or ambient light sensor. The use of power line communication (PLC) or wireless control technology can provide highly flexible LED area lighting control, such as time-based light output level centralized control, vehicle flow sensor based illumination level control, and control based on detection of people and vehicle activity. Downtown lighting, taking care of walking cars and street lighting. LED smart control technology saves power and does not compromise safety. Typical applications include smart dual-brightness lighting, such as parks, gas station ceilings, parking lots, stairs, and refrigerator cabinet lighting that support lighting levels that adjust brightness levels as needed. LEDs can be turned on and off instantly, allowing for easy adjustment of lighting levels based on motion or activity in these applications, such as providing 20%-40% brightness levels when no activity is detected and 100% when activity is detected Brightness lighting. This will save a lot of extra power consumption. 1) Distributed/modular solutions for applications such as linear lamps and trunking lamps In the high-power LED area lighting application, a common power supply architecture is a three-stage architecture of "power factor correction (PFC) + constant voltage (CV) + constant current (CC)". In this architecture, the AC input power supply is regulated by a power factor correction and isolated DC-DC conversion, and a fixed voltage of 24 to 80 Vdc is output to the constant current LED of the built-in DC-DC buck converter circuit. Module (see Figure 2). The design of this architecture provides a modular approach that can be upgraded in the field. The number of LED strips can be flexibly changed according to actual needs, thereby increasing or decreasing the light output to meet the requirements of specific regional lighting applications. Under this light bar, AC-DC conversion and LED driver circuits are not integrated, but distributed configuration, which simplifies safety considerations and enhances system flexibility. Typical applications include linear lighting and cove lighting. Figure 2: Schematic diagram of a typical modular LED area lighting power supply architecture Under this modular approach, a design can be extended for multiple light output levels. Moreover, as the LED light output performance is enhanced, the LED module must provide the same light output level, and the required light bar is better. Each strip has a dedicated DC-DC LED driver, such as the CAT4201 high-efficiency buck LED driver from ON Semiconductor. Optimized for driving high current LEDs, the CAT4201 features a patented switching control algorithm that delivers energy efficient and accurate LED current regulation (up to 350 mA). The CAT4201 can be powered from a supply voltage of up to 36 V and is compatible with 12 V and 24 V standard lighting systems. Figure 3 shows the high-voltage LED driver configuration of the CAT4201. The surrounding N-channel MOSFETs support high-voltage inputs: LED power is 30 W at 100 V input voltage and 13 W at 50 V input. Figure 3: CAT4201 High Voltage LED Driver Configuration 2) Integrated/single-stage solution for applications such as wall washers and exterior wall lamps Not all regional lighting applications require a distributed/modular solution. With the rapid improvement of white LED performance, new LEDs can be used with the new LED driver design method. Leading LED manufacturers have introduced new LEDs that support higher currents and higher luminosity, such as Cree's XP-G series LEDs (with a forward voltage drop of 3.3 V) delivering 330 lumens at 1 A. Seoul Semiconductor's P7 series LEDs (3.3 V forward voltage drop) provide 400 lumens of light output at 1.4 A. Under these conditions, a novel LED driver can be configured to directly drive a large current of 1 A to 3 A. For example, ON Semiconductor's NCL30001 power factor correction TRIAC dimmable LED driver can be used. The NCL30001 is a monolithic/single-segment LED driver solution that combines a PFC and isolated DC-DC converter circuit and provides a constant current to drive the LED directly. This solution is equivalent to integrating the AC-DC conversion with the LED driver two-part circuit, all located in the lighting fixture, saving the linear or DC-DC converter integrated in the LED strip. This monolithic solution has fewer power conversion segments, reduces component usage (such as optical components, LEDs, electronic components, and printed circuit boards), reduces system cost, and supports higher overall energy efficiency of LED power supplies. Of course, this solution has higher power density and may not be suitable for all regional lighting applications. Its optical pattern may be more suitable for lower power LEDs. Typical applications include LED street lights, exterior wall lights, wall washers and refrigerator cabinets. Lighting, etc. 
