What's the reason for the LED bulb strobe?
If this resonant characteristic causes the input current to fall below the TRIAC sustaining current, the TRIAC will turn off. After a short delay, the TRIAC usually switches on and fires the same resonance. In the 1.5 cycle of the input power waveform, this series of events may be repeated several times to form visible LED flashes. To cope with this problem, a key requirement of TRIAC dimming is that the input capacitance of the EMI filter is very low and that the capacitor is decoupled through the TRIAC and the winding impedance. According to the formula, if the capacitance of the dimming module is reduced, the resistance of the resonant circuit can be increased, and the oscillation is suppressed in principle, and the desired circuit work is resumed.
Currently on the market with single stage PFC driver circuit, there will be strobe, causing the flash because the ripple is too large. Single stage pFC circuits are not possible
In addition, electromagnetic interference (EMI) filters are also required, even in LED drive applications that provide excellent power factor correction and support TRIAC dimming. The transient current caused by the TRIAC step (step) will excite the natural resonance of the inductance and capacitance in the EMI filter.
8W offline LED driver GreenPoint reference design with solid state lighting standard energy star "as an example, the sine wave regulator side flyback power conversion does not provide constant energy to the primary bias, dynamic self supply (DSS) circuit can be activated and the light induced flicker. To avoid this problem, it is necessary to allow primary bias to be discharged at each half cycle, and accordingly, the values of the capacitance and resistance that constitute the bias circuit need to be appropriately chosen.
Common causes and treatment of LED light flashing:Generally, the human eye can detect light flashes with frequencies up to 70 Hz, which are not sensed above this frequency. Therefore, in LED lighting applications, if the pulse frequency appears below 70 Hz low-frequency components, the human eye will feel flashing. Of course, in specific applications, there are a variety of factors that may cause LED lights to flicker. For example, in offline low power LED lighting applications, a common power topology is an isolated flyback topology.
