Abstract: In a lamp driving circuit for operating a high intensity discharge lamp, an a commutation circuit comprises at least two switching devices. The switching devices are alternately switched active at a commutation frequency. The active switching device switches at a switching frequency. During an ignition mode, the switching frequency and the commutation frequency are substantially equal. A resulting commutation voltage is supplied to an inverter resonant circuit for generating a supply current. At a node of the inverter resonant circuit, a clamping circuit limits the generated voltage to a predetermined maximum voltage. The voltage at said node of the inverter resonant circuit is applied to an output resonant circuit. The output resonant circuit operates in the ignition mode as a resonator for generating a high ignition voltage; in a steady state operation mode, the output resonant circuit operates as a low-pass filter for reducing a high frequency current component in a lamp current.

Abstract: In a lamp driving circuit for operating a high intensity discharge lamp, an a commutation circuit comprises at least two switching devices. The switching devices are alternately switched active at a commutation frequency. The active switching device switches at a switching frequency. During an ignition mode, the switching frequency and the commutation frequency are substantially equal. A resulting commutation voltage is supplied to an inverter resonant circuit for generating a supply current. At a node of the inverter resonant circuit, a clamping circuit limits the generated voltage to a predetermined maximum voltage. The voltage at said node of the inverter resonant circuit is applied to an output resonant circuit. The output resonant circuit operates in the ignition mode as a resonator for generating a high ignition voltage; in a steady state operation mode, the output resonant circuit operates as a low-pass filter for reducing a high frequency current component in a lamp current.

Abstract: A DC-to-DC converter comprising an input inductor which is connected to an input terminal, an output inductor which is connected to an output terminal, a capacitor which is connected in series with and between the inductors, a switch element which is connected via a first resistor to a common input/output conductor and to a first node that is common to the input inductor and the capacitor, and a diode which is connected via a second resistor to the common input/output conductor and to a second node that is common to the output inductor and the capacitor, the switch element being responsive to a switch control signal (Vsw) applied thereto for alternately making the switch element conducting and non-conducting such that currents flowing through the inductors flow through the switch element or through the diode during an on-interval and an off-interval of the switch control signal (Vsw), respectively, a control circuit having at least one measurement input for receiving a current measurement voltage (Vx) across