An embodiment voltage converter includes a first transistor connected between a first node of the converter and a second node configured to receive a power supply voltage, a second transistor connected between the first node and a third node configured to receive a reference potential, a first circuit configured to control the first and second transistors, and a comparator configured to compare a first voltage with a threshold, the first voltage being equal, during a first period, to a first increasing ramp and, during a second period, to a second decreasing ramp, the threshold having a first value during the first period and a second value during the second period, the first and second values being variable.