Electric power source device

An electric power source device comprising:

• a transformer comprising a primary coil and a secondary coil;
• primary side semiconductor components equipped with semiconductor elements and connected to the primary coil of the transformer;
• secondary side semiconductor components equipped with semiconductor elements and connected to the secondary coil of the transformer;
• a secondary side circuit formed by secondary side electrical components and the secondary side semiconductor components;
• a base plate having a mounting surface on which the transformer, the primary side semiconductor components, the secondary side semiconductor components and the secondary side electrical components are mounted;
• and
• a circuit substrate on which substrate side electrical components are mounted,
• wherein at least two selected from the primary side semiconductor components, the secondary side semiconductor components, and a combination of the transformer and the secondary side semiconductor components are stacked to form a stacked section in a direction of a normal line of the mounting surface of the base plate, and
• at least a part of the substrate side electrical components is arranged inside of an exterior part of a component having a maximum exterior size forming the stacked section in a horizontal direction, which is perpendicular to the direction of the normal line of the mounting surface of the base plate, and this part of the substrate side electrical components is arranged inside of a second surface of the stacked section toward the mounting surface side in a vertical direction, where the second surface of the stacked section is opposing to a first surface of the stacked section which is directly in contact with the mounting surface of the base plate when viewed in the vertical direction which is parallel to the direction of the normal line of the mounting surface.