Editor's Note : Under the background of global energy shortage and increasing environmental protection requirements, all countries in the world have vigorously developed green and energy-saving lighting. As a revolutionary energy-saving lighting technology, LED lighting is rapidly developing. 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.
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.
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 Based on AP3766 LED driver circuit schematic
The program features 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 0.6 Ω A 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.
5 Safe and reliable, isolated output, with output open circuit protection, over voltage protection and short circuit protection.
6 The power switch tube adopts a triode, which eliminates the high-voltage FET and has low system cost.
Figure 2 is a physical picture of the 5W application circuit prototype of the solution. Figure 3 is a photo of a 5W LED driver based on the AP3766. Figure 4 shows the full load efficiency of the 5W LED driver circuit based on AP3766 as a function of AC input voltage. Figure 5 shows the full-load output IV characteristic curve of the 5W LED driver circuit based on AP3766.
Figure 2 Photograph of the 5W LED driver circuit prototype based on AP3766
Figure 4 Based on AP3766 5W LED drive circuit efficiency curve zca2000
Figure 5 5W based on AP3766
10～60W power LED street light, LED straight tube lamp application program
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