Voltage conversion circuits can be used to supply energy to electric loads. For example, in an illumination application light emitting diodes (LEDs) are supplied by such circuits. To this end a controlled voltage is provided to a first connection of a LED or a string of LEDs in a pulsed fashion. This can for example be done by switching a current through the LEDs on and off depending on a pulse-width modulated signal. For controlling the voltage at the first connection of the voltage conversion circuit, a voltage at a second connection of the LEDs can be compared to a reference voltage during a current flowing through the LEDs. If the current is switched off, the voltage at the second connection changes towards the controlled voltage at the first connection. As a consequence, a comparison is not possible in the switched-off state. As therefore only a limited time for controlling the voltage at the first connection is available, controlling may become inaccurate.