LED arrangement of the LED light source and determines the specification of the basic requirements of the drive. The main function of the LED driver is to limit the current flowing through the LED under certain operating conditions, regardless of the input and output voltage changes. The most common is the use of transformers for electrical isolation. The paper discusses the factors that need to be considered in LED lighting design . First, the general requirements for LED drivers Driving LEDs faces many challenges. For example, the forward voltage will change with temperature and current. The LED forward voltage of different individuals, different batches, and different suppliers will also vary. In addition, the color of the LED The point will also drift as the current and temperature change. In addition, multiple LEDs are often used in applications, which involves the arrangement of multiple LEDs. Among the various arrangements, it is preferred to drive a single string of LEDs in series because this method provides excellent current matching performance regardless of how the forward voltage changes and how the output voltage (Vout) "drifts". Of course, users can also use parallel, series-parallel combinations and cross-connects (Figure 1) for other applications that require "mutually matched" LED forward voltage and other advantages. For example, in a cross-connect, if one of the LEDs is open due to a fault, only one of the LEDs in the circuit will double the drive current, minimizing the impact on the overall circuit. Figure 1: Common LED arrangement The arrangement of the LEDs and the specification of the LED source determine the basic driver requirements. The main function of the LED driver is to limit the current flowing through the LED under certain operating conditions, regardless of the input and output voltages. The basic working circuit diagram of the LED driver is shown in Figure 2. The so-called "isolation" means that there is no physical electrical connection between the AC line voltage and the LED (ie, input and output). The most common is to use a transformer for electrical isolation. "Non-isolated" does not use high-frequency transformers for electrical isolation. Figure 2: Schematic diagram of the basic working circuit of the LED driver It is worth mentioning that in the LED lighting design, the AC-DC power conversion and constant current drive can be configured in different configurations: 1) The integral configuration, that is, the fusion of the two, is located in the lighting fixture, the advantages of this configuration include optimizing energy efficiency and simplifying installation; 2) Distributed configuration, ie both exist separately, this configuration simplifies security considerations and increases flexibility. LED driver can work with constant voltage (CV) output according to different application requirements, that is, the output voltage is clamped under a certain current range; it can also work with constant current (CC) output, and the output design can strictly limit the current; A constant current constant voltage (CCCV) output operation may be used, which provides a constant output power, so the current is determined as the forward voltage of the LED of the load. In general, LED lighting design needs to consider the following factors: Output power: related to LED forward voltage range, current and LED arrangement, etc.  Power supply: AC-DC power supply, DC-DC power supply, direct AC power supply  Functional requirements: dimming requirements, dimming methods (analog, digital or multi-level), lighting control  Other requirements: energy efficiency, power factor, size, cost, troubleshooting (protection characteristics), standards to be followed, reliability, etc.  More considerations: mechanical connection, installation, repair/replacement, life cycle, logistics, etc. Optical Rotary Sensor,Custom Encoder,Optical Encoder 6Mm Shaft,Handwheel Pulse Generator Jilin Lander Intelligent Technology Co., Ltd , https://www.jllandertech.com