a surface mounting area used to selectively mount thereon a first three-terminal regulator IC including an input terminal pin, an output terminal pin and a ground terminal pin arranged in a certain pattern, and a second three-terminal regulator IC including an input terminal pin, an output terminal pin and a ground terminal pin arranged in another pattern;

a pad device including first to fourth pads arranged on the surface mounting area along one side thereof, with a preset gap defined between each pair of adjacent ones of the pads, the first to third pads forming a first land for mounting the first three-terminal regulator IC, the second to fourth pads forming a second land for mounting the second three-terminal regulator IC; and

a radiator-side pad device including a first radiator pad and a second radiator pad arranged on the surface mounting area along another side thereof, with a preset gap defined therebetween, and a common radiator pad interposed between the first and second radiator pads, the ground terminal pin being connected to the first radiator pad and the common radiator pad when the first three-terminal regulator IC is mounted on the first land, the output terminal pin being connected to the second radiator pad and the common radiator pad when the second three-terminal regulator IC is mounted on the first land.