Dc/dc converter

A DC/DC converter comprising:

• a choke coil;
• a first input/output unit and a second input/output unit, either one of which serves as an input unit and the other of which serves an output unit;
• a first switching element that connects the first input/output unit and one end of the choke coil during ON-state and disconnects the connection between the first input/output unit and one end of the choke coil during OFF-state;
• a second switching element that is disposed between a first connection point between one end of the choke coil and the first switching element and GND, connects the first connection point and the GND during ON-state, and disconnects the connection between the first connection point and the GND during OFF-state;
• a third switching element that connects the second input/output unit and the other end of the choke coil during ON-state and disconnects the connection between the second input/output unit and the other end of the choke coil during OFF-state;
• a fourth switching element that is disposed between a second connection point between the other end of the choke coil and the third switching element and the GND, connects the second connection point and the GND during ON-state, and disconnects the connection between the second connection point and the GND during OFF-state;
• a first controller that controls ON/OFF of the first switching element and the second switching element;
• a second controller that controls ON/OFF of the third switching element and the fourth switching element;
• and
• a charge pump circuit that supplies power to the first controller and the second controller, wherein
• when stepping up DC voltage input to the first input/output unit to be output to the second input/output unit or when stepping down DC voltage input to the second input/output unit to be output to the first input/output unit,
• the second controller outputs to the charge pump circuit a control signal for controlling the fourth switching element so as to alternately repeat ON-state or OFF-state when the first switching element is ON-state and the second switching element is OFF-state, and
• when stepping up DC voltage input to the second input/output unit to be output to the first input/output unit or when stepping down DC voltage input to the first input/output unit to be output to the second input/output unit,
• the first controller outputs to the charge pump circuit a control signal for controlling the second switching element so as to alternately repeat ON-state or OFF-state when the third switching element is ON-state and the fourth switching element is OFF-state.