Abstract: The invention provides a power conversion device operable in a discontinuous conduction mode under the control of a switch. During operation in the discontinuous conduction mode, an oscillating voltage exists across the switch means prior to a turn-on of the switch means. The power conversion the device comprises a switching controller arranged to ensure that turn-on of the switch occurs at a minimum of the oscillating voltage. The power conversion device also comprises a timer arranged to provide a controlled time period following a first turn-on of the switching means, during which a second turn-on of the switching means can not occur. Such an arrangement is advantageous in that a low power level of operation of the device and a short conduction time of the switch means does not lead to an undesirable increase in switching frequency. Consequently, a reduction in a parasitic capacitance of the switch will be rewarded by an increase in efficiency.

Abstract: A method of operating a power conversion device comprises the steps of operating the power conversion device in sequential switching cycles, each switching cycle including a first conduction period during which an amount of power to be passed from the power conversion device is defined, a second conduction period during which the amount of power is passed from the power conversion device, and an idle period. Substantially constant initial conditions are established at the start of each switching cycle.

Abstract: The invention provides a power conversion device operable in a discontinuous conduction mode under the control of a switch. During operation in the discontinuous conduction mode, an oscillating voltage exists across the switch means prior to a turn-on of the switch means. The power conversion the device comprises a switching controller arranged to ensure that turn-on of the switch occurs at a minimum of the oscillating voltage. The power conversion device also comprises a timer arranged to provide a controlled time period following a first turn-on of the switching means, during which a second turn-on of the switching means can not occur. Such an arrangement is advantageous in that a low power level of operation of the device and a short conduction time of the switch means does not lead to an undesirable increase in switching frequency. Consequently, a reduction in a parasitic capacitance of the switch will be rewarded by an increase in efficiency.