Dc-dc converter

A direct current (DC)-DC converter, comprising:

• a bus having a positive end, a negative end, and an intermediate node;
• a first switch device having one end coupled to the positive end of the bus and another end coupled to a first intermediate node;
• a second switch device having one end coupled to the first intermediate node and another end coupled to a reference end;
• a third switch device having one end coupled to the reference end and another end coupled to a second intermediate node;
• a fourth switch device having one end coupled to the second intermediate node and another end coupled to the negative end of the bus;
• a first capacitor having one end coupled to the positive end of the bus and another end coupled to the intermediate node of the bus;
• a second capacitor having one end coupled to the intermediate node of the bus and another end coupled to the negative end of the bus;
• a flying capacitor having a positive end coupled to the first intermediate node and a negative end coupled to the second intermediate node;
• and
• a protective circuit having a clamping unit and a buffering unit, wherein the first intermediate node and the second intermediate node are coupled to the intermediate node of the bus through the protective circuit.