Abstract: A light-emitting diode (LED) device for preventing soft-start flicker includes an LED module, a voltage converter, a variable current load and a loop control unit. The loop control unit is coupled to the LED module, the voltage converter and the variable current load, and includes a soft-start unit and a dimming control unit. The soft-start unit is utilized for activating a soft-start mechanism of the voltage converter when power of the LED device is turned on. The dimming control unit is utilized for controlling the variable current load to progressively increase a load current of the LED module to a target value and to maintain the load current on the target value until the soft-start mechanism is completed, so as to perform dimming control on the LED module.

Abstract: An oscillator circuit including a charge/discharge unit, a capacitance amplifier, and a level detection circuit is provided. The charge/discharge unit is used to receive a control signal, and perform a charge or discharge operation on a charge/discharge terminal according to the control signal. The capacitance amplifier, including a first impedance, a second impedance, a voltage follower, and a capacitor, is capable of providing an equivalent capacitance with amplifying characteristics. An input terminal of the level detection circuit is electrically connected to the charge/discharge terminal of the charge/discharge unit, and the level detection circuit generates the control signal to the charge/discharge unit according to the charge/discharge terminal of the charge/discharge unit. The oscillator circuit of the present invention may use a capacitance with a smaller level to provide an equivalent capacitance with amplifying characteristics, and thus achieve an oscillator function.

Abstract: A power converter apparatus for receiving an input voltage and produces an output voltage by converting includes a switching-type voltage converting circuit circuit and a voltage level tuning circuit. The switching-type voltage converting circuit circuit includes an inductor, a switch and a synchronous rectifier, wherein the switch is for disabling/enabling the energy-storing operation conducted by the inductor. The synchronous rectifier produces the output voltage by using the stored electrical energy during the above-mentioned energy-storing operation. Besides, the voltage level tuning circuit is across coupled onto the switch for reducing the voltage difference between the two terminals of the switch.