Common causes and treatment methods of LED lamp flashing

Usually the human eye can perceive the frequency of 70Hz light flashes, above this frequency will not perceive. Therefore, in the LED lighting applications, if the pulse signal frequency is lower than the low-frequency component of the 70Hz, the human eye will feel the flicker.

Of course, in specific applications, there are a variety of factors may cause LED lights flashing. For example, in a low power LED lighting application, a common power supply topology is an isolated flyback topology. In order to avoid this problem, the primary bias must be partially discharged in each half cycle, and accordingly, the amount of capacitance and resistance that is appropriate to form the bias circuit is required.

Common causes and treatment methods of LED lamp flashing

In addition, even in the use of excellent power factor correction, TRIAC dimming LED driver applications, but also the requirements of electromagnetic interference (EMI) filter. The transient current caused by the TRIAC step (step) will excite the natural resonance of the inductor and capacitor in the EMI filter. If the resonant characteristics cause the input current to fall below the TRIAC sustain current, the TRIAC will turn off. After a short delay, the TRIAC will normally turn on and excite the same resonance.

In the 1.5 cycle of the input power waveform, this series of events may be repeated several times to form a visible LED flash. In order to deal with this problem, TRIAC dimming is a key requirement of the EMI filter input capacitance is very low, and this capacitor to be able to TRIAC and winding impedance decoupling. According to the formula, if the capacitance of the dimming module is reduced, the resistance of the resonant circuit can be increased.