The LED driving power supply for general lighting generally adopts a flyback converter circuit topology based on a PWM controller. Although this solution has a simple structure, it is generally not possible to use a traditional incandescent lamp with a triac (TRIAC) dimmer to dim the LED. This is because the incandescent lamp is a purely resistive load, and the AC / DC power supply The situation of the system is completely different from that of incandescent lamps. Use the iW3610 AC / DC digital power controller to construct a flyback LED driver, which can be compatible with all types of dimmers. The dimming range is 2% to 10%, and there is no flicker. When there is no dimmer The power factor reaches 0.9 and the coefficient efficiency reaches 85%.
1 Structure and characteristics of iW3610
The iW3610 is packaged in an 8-pin SOIC. The pin configuration is shown in Figure 1.
The iW3610 chip integrates the startup and input voltage detection circuit, feedback signal adjustment circuit, A / D converter, D / A converter, dimmer detection and phase measurement circuit, constant current control circuit, overcurrent protection comparator, peak current Limit the comparator, chopping (chopping) circuit MOSFFT gate driver above the main power supply MOSFET gate driver, etc., as shown in Figure 2.
The functions of each pin of iW3610 are as follows.
Pin 1 (OUTPUT (TR)): MOSFFT switch gate drive output of the chopper circuit.
Pin 2 (VSENSE): Transformer auxiliary winding sensing signal input, used for secondary side voltage feedback to adjust the output.
Pin 3 (VIN): rectified output voltage detection signal input, used for dimmer phase detection, input undervoltage / overvoltage protection, and provides power supply current for the chip during startup.
Pin 4 (VT): external shutdown control terminal. If the shutdown control is not used, a resistor should be connected to ground.
Pin 5 (GND): Ground pin.
Pin 6 (TSENSE): Primary current sensing input, used for cycle-by-cycle peak current control.
Pin 7 (OUTPUT): Flyback converter MOSFET switch gate drive output.
Pin 8 (VCC): controller power supply, start threshold is 12V, undervoltage shutdown threshold level is 7.5V.
iW3610 uses digital control technology, including: chopper circuit, its role is to improve the power factor, to provide dynamic impedance for the dimmer; isolated flyback circuit topology, provides a low-cost solution, allowing the use of traditional incandescent lamp dimmer pair LED dimming. The iW3610 can detect the type of wall dimmer and measure the phase. The iW3610 switches in valley mode, and the efficiency can reach 85% without a dimmer. iW3610 adopts primary side feedback constant current control technology to obtain LED current regulation with tolerance of ± 5%.
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power Cord, ac power cord, ac power cable, power cord wire, heavy duty extension cord, power cord with plug
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