A load-switch voltage control circuit includes a power control circuit for controlling a switching element that stabilizes the voltage to a load. The power control circuit determines intervals of conduction for the switching element, that connects a control impedance to the load, for stabilizing the voltage across the load.

A dimmable instant-start ballast for a plurality of LED lamps and/or a plurality of fluorescent lamps is provided, which includes an isolated dimming interface, a duty control device, a dimming switch, and an inverter circuit. The isolated dimming interface receives a dimming signal to generate a dimming voltage. The duty control device generates an operation signal according to the dimming voltage. The dimming switch periodically couples a first node to a ground according to the operation signal. The inverter circuit receives a rectified voltage and is coupled to the first node. When the first node is coupled to the ground terminal, the inverter circuit provides a lamp current for the LED lamps and/or the fluorescent lamps.

A dimmable instant-start ballast for a plurality of LED lamps and/or a plurality of fluorescent lamps is provided, which includes an isolated dimming interface, a duty control device, a dimming switch, and an inverter circuit. The isolated dimming interface receives a dimming signal to generate a dimming voltage. The duty control device generates an operation signal according to the dimming voltage. The dimming switch periodically couples a first node to a ground according to the operation signal. The inverter circuit receives a rectified voltage and is coupled to the first node. When the first node is coupled to the ground terminal, the inverter circuit provides a lamp current for the LED lamps and/or the fluorescent lamps.

A driving device provides output power to an illumination device including a plurality of filaments is provided. A first converting module converts input power into direct current (DC) power. The first converting module includes a pair of first input terminals receiving the input power and a pair of first output terminals coupled to a first node and a second node and outputting the DC power. A first capacitor is coupled between the first node and a third node. A second capacitor is coupled between the second and third nodes. The first clamping module is connected to a first specific capacitor in parallel. The first specific capacitor is the first capacitor or the second capacitor. A second converting module converts the DC power to generate the output power.