US Patent 7741787 Light-emitting diode driving circuit

A light-emitting diode driving circuit includes a control circuit, a transistor switch and a compensating circuit. The control circuit receives an oscillating signal to generate a pulse drive signal. The transistor switch is activated by the pulse drive signal such that an inductor is charged by an input voltage, in which the inductor is arranged to deliver an inducting current to at least one light-emitting diode when the transistor switch is deactivated. The compensating circuit is coupled between the control circuit and a capacitor provided for reducing ripples of an output voltage corresponding to the inducting current. The compensating circuit performs a charging and discharging operation along with the capacitor when controlled by a dimming control signal provided to control brightness of the light-emitting diode.