To remarkably reduce the risk of interference to adjacent circuits by switching a DC-DC converter that is actuated according to the principle of the pulse modulation.

The DC-DC converter comprises a switching device (1) that can be switched by periodic reference signals (Uref) between an open state and a closed state. The duty cycle of the reference signal determines the ratio of an input signal (Vcc) of the DC-DC converter to an output voltage (Vout). Reference frequency sources (6, 7, 8 and 9) for sending the reference signals (Uref) include modulation circuits (6) for modulating frequencies and/or the reference signals.