Dc-dc converter and power supplying system including same

A DC-DC converter comprising:

• a first-voltage-side port and a second-voltage-side port both of which are input ports, respectively;
• a third-voltage-side port which is an output port;
• a reference-voltage terminal common for inputting and outputting;
• first to fourth switching devices;
• a transformer including a core and a primary winding and a secondary winding both wound around the core:
• a backflow prevention diode having an anode connected to the first-voltage-side port;
• and
• a backflow prevention switching device having one end connected to the second-voltage-side port;
• the first switching device having one end connected to another end of the backflow prevention switching device, wherein
• the second switching device has one end connected to a cathode of the backflow prevention diode;
• the primary winding has one end connected to another end of the first switching device;
• the secondary winding has one end connected to another end of the second switching device;
• a first diode has a cathode connected to another end of the first switching device and has an anode connected to the reference-voltage terminal;
• a second diode has a cathode connected to another end of the second switching device and having an anode connected to the reference-voltage terminal;
• a third diode has an anode connected to another end of the primary winding and having a cathode connected to the third-voltage-side port;
• a fourth diode has an anode connected to another end of the secondary winding and having a cathode connected to the third-voltage-side port;
• the third switching device has one end connected to another end of the primary winding and having another end connected to the reference-voltage terminal;
• and
• the fourth switching device has one end connected to another end of the secondary winding and has another end connected to the reference-voltage terminal.