Patent ID: 8258711

Claim:
A semiconductor device used for driving an LED and using a vertical semiconductor device in which a current is flown in a vertical direction, wherein the vertical semiconductor device is formed of a vertical MOSFET, a main device functioning as a constant-current driving device and a subsidiary device functioning as a circuit-breaking switch during dimming are formed inside a chip of the semiconductor device, which are formed of the vertical semiconductor devices, the main device and the subsidiary device share a drain region, the main device has a first source region and a first gate electrode, the subsidiary device has a second source region and a second gate electrode, and the first source region and the second source region are formed in a first surface of the semiconductor device by doping a first impurity, and are electrically insulated from each other through an isolation region formed in the first surface by doping a second impurity having an opposite polarity to that of the first impurity.