Usually the human eye can perceive frequencies up to 70 Hz flashes of light, higher frequencies are not perceived. So the LED lighting applications, if pulsed signals at frequencies below 70 Hz low frequency components, the human eye blinking would feel. Of course, in the specific application, a variety of factors can lead to LED light is blinking. For example, in the off-low-power LED lighting applications, a common power supply topology is isolated Flyback topology. According to the "Energy Star" solid state lighting standard 8W LED drive GreenPoint® off-line reference design, for example, as the Flyback regulator sine wave power conversion does not give primary bias power, dynamic self supply (DSS) circuit may activate and trigger light blinking. To avoid this problem, you must enable primary bias to partial discharges in each half cycle, accordingly, needs the right choices this biasing circuit of capacitor and resistor value.
In addition, even in the use provides excellent power factor correction, supports TRIAC dimmer LED driver applications, as well as electromagnetic interference (EMI) filtering. The TRIAC step (step) transient currents caused by fires in EMI filter inductance and capacitance of the natural resonance. If this resonance characteristics of input currents down to TRIAC under current, TRIAC will turn off. After a short delay, TRIAC turn-on, usually will, inspire the same kind of resonance. In less than a half cycle of the input waveform, this series of events could be repeated many times, to form a visible LED blinks. In order to deal with this problem, TRIAC dimming a key requirement is that the extremely low input capacitance of EMI filters and capacitors through the TRIAC and winding impedance decoupling. According to the formula, capacitance decreases in the dimming module, you can increase the resistance of the resonant circuit, inhibition of oscillation on principle, and restore the desired circuit.
