A converter for converting a DC input voltage includes two input lines receiving the DC input voltage; at least one normally off semiconductor switch which is not conductive without application of a control voltage to its gate and which is provided in one of the input lines. The converter also includes electric circuitry connected between the input lines and including at least one normally on semiconductor switch which is conductive without application of a control voltage to its gate; and a controller. In operation of the converter, the controller operates the at least one normally on semiconductor switch of the electric circuitry by temporarily applying a first control voltage to its gate; and permanently applies a second control voltage to the gate of the at least one normally off semiconductor switch in the one input line. Any normally on semiconductor switch of the electric circuitry is spatially separated and thus thermally isolated from any normally off semiconductor switch.