On-board power supply device

An on-board power supply device comprising:

• a voltage conversion unit that includes a switching element that switches on and off according to a control signal in which an on signal and an off signal are alternately repeated provided to the switching element, the voltage conversion unit stepping up or stepping down a voltage applied to a first conduction path according to the switching of the switching element between on and off, and applying a voltage to a second conduction path;
• a first voltage detection unit that detects a value of a first voltage that is applied to the second conduction path;
• a second voltage detection unit that detects a value of a second voltage that is applied to a load-side conduction path that is interposed between the second conduction path and a load;
• a target voltage setting unit that sets a target voltage value based on the value of the second voltage detected by the second voltage detection unit;
• and
• a control unit that repeatedly performs feedback calculation for updating a duty ratio of the control signal based on the value of the first voltage detected by the first voltage detection unit so as to bring the value of the first voltage applied to the second conduction path closer to the target voltage value, and outputs the control signal with the updated duty ratio to the switching element each time the duty ratio is updated.