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 voltages. 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, a single string of LEDs in series is preferred because it provides excellent current matching regardless of how the forward voltage changes and how the output voltage (Vout) “driftsâ€.
Of course, users can also use other arrangements such as parallel, series-parallel combination, and cross-connection for applications that require "mutually matched" LED forward voltages 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 to electrically isolate. And "non-isolated" does not use high-frequency transformers for electrical isolation.
Figure 2 Schematic diagram of the basic working circuit of the LED driver
Noah Plus LED Grow Light, Cree LED Grow Light, COB LED Grow Light, UL Certified LED Grow Light
Shenzhen Mingxue Optoelectronics CO.,Ltd , http://www.led-lamp-china.com