Semiconductor device and power supply device using the same

A synchronous-rectification-type power supply device for driving gates of a rectification MOSFET and a commutation MOSFET by a control circuit, one of main terminals of the rectification MOSFET being connected to a positive potential side of a direct-current input power source, an other of the main terminals of the rectification MOSFET being connected to one of terminals of a choke coil and one of main terminals of the commutation MOSFET, an other of the main terminals of the commutation MOSFET being connected to a negative potential side of the direct-current input power source, one of terminals of an output capacitor being connected to an other of the terminals of the choke coil, an other of the terminals of the output capacitor being connected to the other of the main terminals of the commutation MOSFET, one of terminals supplying power to a semiconductor device as a load being connected to the other of the terminals of the choke coil, and an other of the terminals supplying the power to the semiconductor device as the load being connected to the other of the main terminals of the commutation MOSFET,

• wherein a socket mounting the semiconductor device as the load is formed, a first capacitor of the output capacitors is placed at a center of the socket, and a second capacitor, the choke coil, and the semiconductor device are placed around the socket,
• the rectification MOSFET, the commutation MOSFET, and a driving semiconductor element that drives these two MOSFETs are integrated on the semiconductor device, and
• the rectification MOSFET and the commutation MOSFET are laminated via a conductive member, the conductive member is electrically connected to the one of the terminals of the choke coil, and output terminals are placed on a same plane.