DC-DC converter in discontinuous conduction mode and conversion method

The invention discloses a DC-DC converter in a discontinuous conduction mode which can prevent an induction current from dropping to zero in an idle state. The DC-DC converter comprises a signal input end receiving a DC input signal, an output circuit outputting a DC output signal, an inductor for outputting an induction current in an energy storage state according to the DC input signal and outputting the induction current in an energy release state according to the DC input and output signals, a freewheel switch coupled to induction input and output ends and used to be turned on in the idle state according to an idle running control signal and to be not turned on in the energy storage state and the energy release state, a current detection circuit for detecting whether the induction current reaches a current threshold and generating a current detection signal, and a control circuit coupled to the output circuit, the freewheel switch and the current detection circuit and used to generate an idle running control signal according to the current detection signal.