E-transformers are widely used in electronic circuits because of small volume, light weight, low cost, high converting efficiency and good reliability. An E-transformer firstly converts an AC input voltage to a DC voltage, and then converts the DC voltage to a high frequency lower AC voltage via an oscillator.
One application of the E-transformer is to provide driving for LED stings. Prior art using a boost PFC (power factor correction) circuit to drive LED strings, and using a triac to execute phase cut to realize LED dimming. However, conventional E-transformers are designed for halogen lamps, but LEDs have a much lower power level than halogen lamps, so using conventional E-transformers to drive LED may lead to flicker.