Under the background of global energy shortage and increasing environmental protection requirements, all countries in the world have vigorously developed green energy-saving lighting. As a revolutionary energy-saving lighting technology, LED lighting is developing rapidly. However, the requirements for LED drive power are also increasing. High efficiency, high power factor, safe isolation, EMI compliance, high current control accuracy, high reliability, small size, low cost, etc. are becoming key evaluation indicators for LED drive power.
LED drive power requirements
LED is a low-voltage light-emitting device with long life, high light efficiency, safety and environmental protection, and convenient use. For mains AC input power drives, the isolated output is based on safety specifications. The higher the efficiency of the LED driving power supply, the better the LED's high luminous efficiency and energy saving. At the same time, the high switching operating frequency and high efficiency make the entire LED driving power supply easy to install in compact LED lamps. High constant current accuracy guarantees brightness and color consistency when using LED lighting in large quantities.
Power LED lamp cup application scheme below 10W
At present, power LEDs below 10W are widely used, and many integrated products are available, that is, LED driving power and LED lights are integrated in one lamp, which is convenient for users to use directly. Typical lamp specifications are GU10, E27, PAR30 and so on. For this application, we have designed the following scheme (see Figure 1)
Figure 1: Schematic diagram of LED driver circuit based on AP3766
The program features are as follows:
1. Based on the latest LED dedicated driver chip AP3766, the primary side control mode is adopted, and the optocoupler and the secondary current control circuit are not required to realize the isolated constant current output, and the circuit structure is simple. The primary side current is detected by the resistor R5, the primary current peak is controlled to be constant, and the switching duty ratio is controlled, and the on-time of the output diode D1 and the entire switching cycle time ratio are kept constant, and the output current is constant.
2. The AP3766 uses a proprietary “sub-micron startup current†technology that requires only 0.6μA of startup current, thus reducing power dissipation on the startup resistors R1 and R2 and improving system efficiency. Typical 5W application efficiency is greater than 80%, and no-load power consumption is less than 30mW.
3. AP3766 uses constant current tightening technology to achieve vertical constant current characteristics, high constant current accuracy.
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Yuheng Optics Co., Ltd.(Changchun) , https://www.yhenoptics.com