Abstract: The present invention provides a light emitting diode (LED) driving circuit with low harmonic distortion. The LED driving circuit comprises: a rectifying circuit, a linear constant current circuit, a current limiting circuit, and a current limiting ramp slope determining circuit. The rectifying circuit is utilized for rectifying an alternating current (AC) power source to provide a direct current (DC) voltage output. The linear constant current circuit is utilized for driving at least an LED. The current limiting circuit is connected in parallel between the rectifying circuit and the linear constant current circuit, and utilized for generating a current limiting effect and determining a current limiting height. The current limiting ramp slope determining circuit is connected in parallel between the rectifying circuit and the linear constant current circuit and connected in series with the current limiting circuit, and utilized for determining a current limiting ramp slope.

Abstract: The present invention provides a light emitting diode (LED) driving circuit with low harmonic distortion. The LED driving circuit comprises: a rectifying circuit, a linear constant current circuit, a current limiting circuit, and a current limiting ramp slope determining circuit. The rectifying circuit is utilized for rectifying an alternating current (AC) power source to provide a direct current (DC) voltage output. The linear constant current circuit is utilized for driving at least an LED. The current limiting circuit is connected in parallel between the rectifying circuit and the linear constant current circuit, and utilized for generating a current limiting effect and determining a current limiting height. The current limiting ramp slope determining circuit is connected in parallel between the rectifying circuit and the linear constant current circuit and connected in series with the current limiting circuit, and utilized for determining a current limiting ramp slope.

Abstract: An LED driving circuit includes a charging-discharging circuit and a constant-current unit. The charging-discharging circuit is coupled to an AC current source, and includes an impedance, a diode and an energy storing circuit. The energy storing circuit is coupled to the impedance, the diode, and an LED unit. The constant-current unit is coupled to the charging-discharging circuit in series, and is arranged to regulate current. During the positive half cycle of the AC current source, the constant-current unit charges the energy storing circuit via the impedance; and during the negative half cycle of the AC current source, the energy storing circuit provides the LED unit with a discharging current via the diode, making the driving current of the LED driving circuit remain stable even when the AC current changes from the positive half cycle to the negative half cycle, thus preventing the flicker effect.